Chocolate Cassis Cake with Red Currant Raspberry Buttercream and Chocolate Ganache

Or more aptly, chocolate berry cake. There it is - the whole punchline to this post. Tessa Huff's chocolate cassis cake from Layered is beautiful and delicious, but there's no hint, however elusive, of cassis or red currant upon eating it. My co-workers praised this cake, comparing it to Black Forest Cake, Sachertorte,  or simply, Raspberry Chocolate Cake.

A short story

I may have doomed my cake to this raspberry/cherry flavor fate. Not intentionally, but because it is impossible to find red currants in New Jersey. I bought this book in April and have been eyeing this cake ever since. Every time I stop by the grocery store, I look for red currants, fresh or frozen. They don't exist here. This makes some modicum of sense, since although red currants are native to both Western Europe and North America, their growth was federally banned in the early 1900s because of white pine blister rust, a fungal disease requiring two hosts: a white pine and a member of the Ribes family, which includes currants. Although it's been legal to grow red currant bushes federally since the late 1960s, there are still some counties in NJ where it's illegal to grow red currants (whoa). Cultivating European black currants is still prohibited. Decades of prohibition and growth restriction likely impacted demand for these little berries in the US. Plus, they have an extremely short season - two short weeks around June - during which they ripen.

That little history lesson was a bit of a digression from an ordinary blog post about cake, I realize, however its purpose is illustrating that I really tried to locate red currants for the red currant curd and buttercream components of this cake. Failing that, since it isn't cranberry season here yet, I decided the next best thing would be to use a red currant jam* in place of the red currant curd. I even liked the idea a bit better than curd, because as much as I love lemon curd, I thought the jam might balance the richness of the buttercream better. However, everyone thought the red currant filling I spend inordinate amounts of time straining (the original Hero Red Currant Fruit Spread includes seeds), was either raspberry or cherry jam.

In another blow to my cake ego, no one commented on any additional flavor profile in the chocolate cake beyond chocolate, and I certainly wasn't able to taste any crème de cassis (blackcurrant liqueur) in either the batter or the baked cake. Maybe I was expecting too much or too distinctive (tart) a taste. After all, my only exposure to crème de cassis before now comes from a love for Kir Royales. [One intriguing factoid from today: all the girls at work knew what cassis meant, but not a single guy recognized the word.]

Based on browsing around the internet, I still believe I was correct in expecting more of a tart flavor from a recipe involving black and red currants, instead of a general berry-y flavor. The red currant jam was tart when I tried it by itself, but maybe in straining it to remove the stems and seeds, I also removed the compounds that contributed to the tartness of the jam?

Ideas to try next time

I think I would have liked this cake more if I wasn't expecting something more like "chocolate cranberry" rather than "chocolate cherry/raspberry".  I'd like to remake this cake, with either a cranberry or pomegranate curd instead of my red currant jam solution. I think that might add the extra tartness I was hoping to taste. Alternatively, I would suggest either using a little less cream to make the ganache and adding a few tablespoons of crème de cassis instead, or, making a simple pomegranate molasses by simmering 1-2 cups of 100% pomegranate juice for about 30 minutes until it's reduced to ¼-1/2 cup, letting that cool, then brushing it on the cake layers before adding the buttercream.

I might also alter how the cake is frosted. The inside cake layers are frosted with buttercream, which is then hollowed out somewhat in the middle to form a bowl to contain the red currant raspberry curd. In practice, this made cutting the cake into even slices very difficult at room temperature and seemed to crush the interior of the cake layers. On repeating this cake, I wouldn't hollow out the center to create a curd bowl, instead I'd add slightly less buttercream over the top of the layer, then use a buttercream dam around the edges to prevent the curd, lightly spread across almost all of the buttercream surface, from spilling out. One other dilemma I faced was the ganache. I've made Tessa's ganache before for a different cake, and if memory serves, I might have run into a similar problem. Over time, the ganache hardens enough that cutting through it breaks the ganache and makes slicing the cake difficult (on top of the difficulty from the fruit curd/jam). One obvious solution is to serve the cake at a specific time, which makes it easy to strategize cutting it at the optimum time for perfect buttercream and ganache consistency. None of my co-workers were particularly bothered by either of these flaws, and happily ate the cake all the same.

As far as not tasting the crème de cassis in the cake itself, the fault may again lie with the baker (yours truly). One of the things that irks me about Layered is Tessa's use of 6-inch pans to create her gorgeous towering confections. The photographs are lovely, and I'm sure the cakes taste terrific, but I already own three 9-inch cake pans, three 8-inch cake pans, a large bundt cake pan, a tube cake pan (although that's in San Diego), two 9-by-13-inch baking pans, and a variety of other "baking" pans... but just one 6-inch cake pan. A 6-inch pan was never a cake size I'd encountered in baking cookbooks before Miette, and while I know professional bakeries must use them, I have to set some limits on the number of pans in my kitchen.

As you might expect based on the above paragraph, the recipe for this chocolate cassis cake calls for three 6-inch pans. I've modified Tessa's recipes before to work in three 8-inch pans, which is what I did here. However, my three 8-inch layers were quite thin. Perhaps baking this chocolate cassis cake in two 8-inch or 9-inch pans would have been the wiser strategy, because a thicker cake layer might enable the delicate cassis flavor to shine through a little more. Or maybe I should have followed Tessa's exact instructions on prepared the cake (see more detail below). Or maybe my high-octane coffee from Track 5 Coffee in Cranford simply overpowered the cassis. In the end, the cake tasted of neither coffee nor cassis, but simply like a delicate and airy chocolate cake.

Making the chocolate cassis cake

Almost all of Tessa's cakes are project cakes. In a way, that's good, because the added activation energy of knowing that I'll be spending an entire evening making on cake dissuades me from spending every cake in this book (so far). In the process of baking through Layered (I've made her Porter Chocolate Cake with Peanut Butter Cream Cheese Frosting and Chocolate Ganache, Oatmeal Cookie Cake, Brown Sugar Buttermilk Cake, and Classic Chocolate Cake with Raspberry Buttercream so far... and now this), I've learned a few clever tricks - like, why make one small or medium batch of time-consuming Swiss Meringue Buttercream when I can make a large batch and refrigerate or freeze it until I make the next cake. Honestly, the buttercream is really the rate-limiting step in making most of Tessa's cakes (which is what I loved so much about her Porter Chocolate Cake - an easy cream cheese frosting!). Please keep that in mind as you read through the rest of this post and the recipe!

The cake itself is quite easy to make and requires only 30 minutes from start to oven. You'll want to brew fresh, strong coffee first. While that's brewing, add all the dry ingredients to a medium bowl and whisk them to combine. In a mixer bowl or another medium bowl, combine the egg, egg yolk, sour cream, and vanilla. Once you have brewed ¼ cup of coffee, add it to a small saucepan together with a stick of unsalted butter and ½ cup crème de cassis, then bring to a simmer over medium heat. Add the cocoa powder and sugar to the saucepan (still over medium heat), then whisk to combine. Here is where I decided I knew better than Tessa's instructions. She says nothing about cooling the hot chocolate-coffee-butter mixture, but directs the reader to remove the pan from the heat, then stir in the sour cream mixture, then the flour mixture. To me, that seemed like the perfect strategy for cooking/curdling my sour cream mixture and finding unincorporated pockets of flour in the final cake. I decided to let the hot chocolate liquid cool for about 10 minutes, then drizzled it into the sour cream mixture while my stand mixer was running on low. It starts to spatter towards the end of incorporation, so if you follow my lead, be watchful. Scrape down the bowl and contain at the lowest speed if spatter seems imminent. As soon as the chocolate mixture was incorporated, I added the flour in two short additions to enable maximal quick mixing without flour pockets.  With the high amounts of leavening in the cake batter, it started to froth gently as soon as the flour was added. I divided my batter evenly (367 g each) across 3 8-inch pans and baked for about 19 minutes, rotating once.

The cakes should cool in their pan on a cooling rack for 15 minutes, then be turned out to finish cooling on parchment paper on the cooling racks. This cake recipe is rather fragile and sticky, so whatever you do, don't lay the bare cake down on a wire rack (or anything you don't want it sticking too).

As the cake cools, it's time to make the frosting. Since this chocolate cassis cake is frosted in the currently trendy "naked" style (the sides are left bare), you'll only need about 1 ½ - 2 cups of buttercream. I strongly recommend making a full large batch, which yields approximately 6 ½ cups, and refrigerating (10 days) or freezing (1 month) the rest in 1 ½ cup portions for future cake projects. If you still want to make less, it's easy enough to scale down the recipe.

In making the buttercream, you're going to be sweating over the stove for about 15-20 minutes, whisking egg whites and sugar constantly while they heat to 160 F in a mixing bowl over simmering water. This task is significantly easier with a second person (or more) and/or with a saucepan acting as your double boiler bottom that fits your mixing bowl snugly. I have neither of these advantages, so these 20 minutes are certainly the worst part of making meringue frosting. Once down, you quickly move the mixing bowl to your stand mixer, to which you've already attached the whisk attachment, and begin whisking the hot egg white syrup until medium stiff glossy peaks form and the mixing bowl and its contents have cooled to room temperature. While this whisking is going on, you should ensure you have your butter for the buttercream cut into tablespoon chunks. Once the egg whites have reached stiff peaks and are sufficiently cooled, these butter pieces are added a few at a time to slowly incorporate fat into the glossy sugar structure you've just created. For this, you'll switch from a whisk to a paddle attachment. This butter-addition process takes another 30 minutes or so (for a full batch). Do not try to hurry the process, or you risk breaking your buttercream and that's a fate no one wants. Return text messages, read a magazine next to your mixer, talk to someone, do whatever it takes not to get impatient and add butter too quickly. Each addition needs to be fully incorporated before more butter is added. At last, you'll have a glossy, airy, not too sweet buttercream. Add vanilla, and beat for 3-5 minutes. Hurray, you've successfully made a large batch of buttercream! It only took 1 hour(ish), some sweat (hopefully not into the buttercream), and multiple sticky dishes. But, you have enough frosting for this cake and at least one or two more! So, it's really a big win.

The final substep to making this cake is making a dark chocolate ganache. This part is insanely easy in comparison to everything else. Heat some heavy cream over medium-low heat until it simmers, then pour it over your chopped dark chocolate. Let it sit 30 seconds, then whisk together to form a smooth ganache. Set aside while you begin assembling the cake. Tessa calls for a ½ portion of her chocolate ganache recipe. I made a full portion, intending to save half for another cake, but found that I didn't have too much and wound up using the whole amount on my top cake layer.

At last, it's time to frost the cake. For her 6-inch layers, Tessa used 1 ½ cups of frosting with 3 tablespoons of red currant raspberry curd. For my 8-inch layers, I used 2 cups of frosting mixed with 6 tablespoons of strained red currant jam. I had heated my jam in 10-second intervals for about 20 seconds total to liquefy it enough to strain it; if you're using jam as well, you'll want to do something similar here. Place the first layer down on your serving dish, then add a generous ¾ - 1 cup buttercream on top. Make a shallow bowl in the frosting (hollow it out somewhat at the center of the cake), then add about ½ cup of red currant raspberry curd or fruit jam. Top with the second layer of cake. Repeat the frosting and curd/jam layers, then top with the final cake layer. Carefully spread your still-liquid (but not hot) ganache on top of the cake. Decorate if desired, with little ganache kisses and fresh red currants (or raspberries).

This cake will keep for up to three days in the refrigerator. It should come up to room temperature before serving, otherwise the buttercream may be too hard.

Chocolate Cassis Cake with Red Currant Raspberry Buttercream and Chocolate Ganache

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Course: Dessert

Prep Time: 1 hour hour 30 minutes minutes

Cook Time: 55 minutes minutes

Total Time: 2 hours hours 25 minutes minutes

Servings: 10 -12 slices

Ingredients

Red Currant Raspberry Curd*

• ½ cup 75 g red currants (with stems)
• ½ cup 80 g fresh raspberries
• 5 tablespoons 70 g unsalted butter, cubed
• 1 large egg
• 2 large egg yolks
• ¾ cup 150 g granulated sugar

Chocolate Cassis Cake

• 1 ½ cups 190 g all-purpose flour
• 1 teaspoon baking soda
• ¾ teaspoon baking powder
• ½ teaspoon salt
• ¼ cup 60 ml strongly-brewed coffee
• ½ cup 120 ml crème de cassis**
• ½ cup 115 g/1 stick unsalted butter
• ½ cup 120 ml full-fat sour cream
• 1 large egg
• 1 large egg yolk
• 2 teaspoons pure vanilla extract
• ½ cup 50 g unsweetened cocoa powder
• 1 ½ cups 300 g granulated sugar

Vanilla Swiss Meringue Buttercream***

• 1 cup 240 ml large egg whites
• 2 cups 400 g granulated sugar
• 3 cups 675 g/6 sticks unsalted butter, cubed, at room temperature
• 1 tablespoon pure vanilla extract

Dark Chocolate Ganache****

• 1 cup 6 ounces/170 g chopped dark chocolate (60-85% cacao)
• ½ cup 120 ml heavy cream

Instructions

Red Currant Raspberry Curd

• Add the currants and raspberries to a saucepan.
• Heat over medium-high heat for about 10 minutes, until berries begin to break down and currants can be crushed with the back of a wooden spoon. Remove from heat.
• Strain cooked fruit through a fine-mesh sieve, pressing fruit against the sides to extract the maximal amount of juice. This effort may take anywhere from 10-30 minutes, depending on the size and fineness of your strainer. Discard stems, seeds, and other solids.
• Place cubed butter in a heatsafe bowl and set aside.
• In a medium saucepan, add ¼ cup plus 1 tablespoon (75 ml) currant-raspberry juice, egg, egg yolks, and sugar, then whisk to combine.
• Cook over medium heat for 6-8 minutes, stirring constantly to keep eggs from curdling, until mixture thickens enough to coat the back of a spoon, or reaches 160 F on a candy thermometer.
• Remove from heat and strain through a clean, fine mesh sieve into the butter-containing bowl. Stir to combine. Cover with plastic wrap, pressing the plastic wrap down onto the surface of the curd to prevent formation of a skin. Refrigerate until set, at least 4 hours.
• Curd may be stored in a glass jar up to 1 month in advance.

Chocolate Cassis Cake

• Preheat oven to 350 F (175 C). Grease and flour three 8-inch or 6-inch cake pans.*****
• Whisk together flour, baking soda, baking powder, and salt. Set aside.
• Beat together the sour cream, egg yolk, and vanilla in the bowl of a stand mixer or other large bowl.
• Add the coffee, cassis, and butter to a medium saucepan. Place over medium heat until butter melts.
• Whisk the cocoa powder and sugar into the cassis mixture. Once combined, remove from heat and let cool briefly.
• Drizzle cassis mixture into the sour cream mixture while the mixer is running at low speed to combine. Scrape down sides of bowl.
• Add the dry ingredients, beat on low or whisk until just combined.
• Even divide batter amongst prepared pans (367 g batter each).
• Bake for 18-19 minutes in 8-inch pans or 22-25 minutes in 6-inch pans, rotating once. An inserted toothpick should come out cleanly.
• Let cool on wire rack for 10-15 minutes, then remove cake from pans onto parchment paper and continue cooling.

Vanilla Swiss Meringue Buttercream

• Place egg whites and sugar together in a bowl from a stand mixer, whisk together to combine. (if you don't have a stand mixer, hopefully you have a hand mixer and compatible metal bowl. This recipe will be nigh impossible to whisk completely by hand.)
• Bring a few inches of water to a simmer in a medium saucepan over medium-high heat.
• Place the mixer bowl over this saucepan to replicate a double boiler. The bottom of the mixer bowl must not touch the simmering water in the saucepan.
• Over the course of about 15 minutes, whisk intermittently as the egg mixture heats to 160 F (70 C) on a candy thermometer. If you don't have a thermometer, it should be hot when tested on the inside of your wrist (don't burn yourself).
• Once hot, carefully fit the mixer bowl onto your stand mixer. Using the whisk attachment, beat the egg white-sugar liquid on high speed for 8-10 minutes, until medium-stiff peaks are formed. Once complete, the mixer bowl should have cooled to room temperature and there should be no residual heat escaping the meringue.
• Swap the whisk for the paddle attachment. Turn the mixer to low speed and begin adding the room temperature butter, 2-3 tablespoons at a time. For a large recipe, this will take about 30 minutes. Once fully incorporated, add the vanilla, and beat at low speed to incorporate. Turn the mixer up to medium-high and beat until silky smooth, about 3-5 minutes.
• Store leftover buttercream in the refrigerator for 10 days or in the freezer for 2 months. Thaw frozen buttercream in the refrigerator and bring stored buttercream to room temperature before using.

Dark Chocolate Ganache

• Place chopped chocolate in a heat-safe bowl.
• Bring the cream to a simmer slowly over medium-low heat in a small saucepan. Take care not to scorch the cream.
• As soon as the cream begins to simmer, pour it over the chopped chocolate.
• Let cream and chocolate stand 30 seconds, then whisk together until smooth (this should take a few minutes).
• Let cool until it has thickened some but is still runny with a spreadable consistency.
• If not using immediately, store in the refrigerator for up to a week. Bring to spreadable consistency by microwaving in short 20 second intervals, stirring in between, or reheat in a double boiler.

Notes

*Alternatively, use 1 ½ cups fruit jam, a different fruit source, or ¼ cup plus 1 tablespoon red currant or pomegranate juice.
**Substitute red currant or pomegranate juice for the creme de cassis.
***Buttercream recipe makes 6 ½ cups, enough to fill and frost a three layer 8-inch cake. You will only need 1 ½ - 2 cups to fill this cake (and other 8-inch naked cakes).
****Ganache recipe makes 1 cup
*****If you only have 9-inch pans, I recommend making this a two layer cake, as there's not enough batter to make three reasonable 9-inch layers.

*I do not advise buying Hero jam online, as it's at least double the cost online as it was at my local supermarket.

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