I promised the recipe for the cake I made last month…so here it is! I wanted a chocolate cake with mocha buttercream (well, more specifically the birthday boy requested that).
This request was based on a grocery store cake we all have really fond memories of eating. Frequently. Too frequently, truth be told. It was my favorite flavor combination, so it jumped in the cart with the dinner groceries a bit too often.
For a birthday celebration, I wanted a little more special version of the cake. And the last few times we’ve gotten it at the grocery store have been not as good as I remembered, anyway.
Scouring the corners of the internet for a recipe, I quickly realized this combination doesn’t seem to exist anywhere, and I would need to marry and modify a couple of recipes to get what I wanted.
I wanted a chocolate cake that was moist but still cake-y, not dense and fudge-y. None of the chocolate cakes I’ve made to date have been exactly what I was looking for.
I found a promising recipe for a chocolate layer cake on Smitten Kitchen. Deb had adapted the recipe from a Gourmet recipe.
Her version has raspberry filling and chocolate ganache, which, while probably delicious, was not what I wanted, but the cake itself had great promise.
I wanted a lighter, airier mocha buttercream, so I decided on a Swiss buttercream. Did you know there are at least 5 different kinds of buttercream? See? I always said buttercream deserved to be its own food group!
I turned to turned to Serious Eats for a Swiss buttercream recipe. I started with a chocolate buttercream recipe which I adapted to a mocha flavor.
Swiss buttercream is made by whisking the egg whites and sugar over a water bath until slightly thickened and frothy, beating it off heat into a meringue and then beating in the softened butter and flavorings slowly. This results in a frosting that is rich and flavorful, but silky smooth and somehow light.
The whole thing is unexpectedly huge. The cake layers are made in a 10” pan, which results in a cake that serves around 16. Sadly, the 3 of us managed to polish off all 16 servings in less than a week. It is THAT delicious.
Chocolate cake with mocha buttercream is the perfect celebration cake
Even the cake alone is incredible, and that is high praise from someone who considers most cake merely a vehicle for consuming frosting…
Chocolate Cake Layers
Makes 2 gigantic layers
Ingredients
1 1/2 cups hot brewed coffee
3 ounces semi-sweet chocolate, coarsely chopped (I used chocolate chips for this)
3 cups granulated sugar
1 1/4 teaspoons fine sea or table salt
3/4 cup vegetable oil
1 1/2 cups buttermilk
3/4 teaspoon vanilla
3 large eggs
2 1/2 cups all-purpose flour
1 1/2 cups unsweetened cocoa powder (NOT Dutch process - this is important for the chemistry to work)
2 teaspoons baking soda
3/4 teaspoon baking powder
Directions
Preheat oven to 300°F (yes, only 300!). This bakes a long time at a lower than normal temp - I have no idea why that is the process, but I assume there is a reason and I don’t want to mess with perfection..
grease two 10×2-inch round cake pans. Line bottoms with rounds of parchment paper and grease paper (I only have one 10” cake pan so I cooked my layers consecutively instead of together.)
Place chopped chocolate in a large bowl and pour hot coffee over it. Let sit together a few minutes, then whisk until chocolate is smooth.
Whisk in sugar, salt, oil, buttermilk, and vanilla until combined.
Whisk in eggs, one at a time.
Sift flour, cocoa, baking soda, and baking powder into a second large bowl, add to wet ingredients and whisk until smooth.
Divide batter between two pans. (Batter for one cake layer weighs about 1008 grams.) Bake cake layers in middle of oven until a toothpick inserted in center comes out clean, 1 hour to 1 hour and 10 minutes - mine took exactly one hour. I had to cook my layers consecutively since I only had one pan - the batter holds up just fine for the second round of baking
Cool 10 minutes in pan, run a knife around edge to loosen and turn layers out onto a cooling rack and remove parchment round. Cool completely before frosting, obviously! I popped the layers into the fridge to complete the cooling because I was in a hurry to get them frosted.
this recipe makes beautiful flat layers perfect for frosting and stacking
Mocha Swiss Buttercream
Enough to generously frost and decorate a 2 layer cake
Adapted from a recipe from Serious Eats
Ingredients
6 egg whites
11 ounces light brown sugar (about 1 2/3 cups)
1 teaspoon kosher salt
1/4 teaspoon cream of tartar
16 ounces unsalted butter (4 sticks), softened to room temperature
8 ounces finely chopped dark chocolate
1 tablespoon instant espresso powder dissolved in a bit of hot water
A drizzle (~1 Tbsp) Kahlua coffee liqueur
Directions
egg whites and sugar thickening over a simmering water bath
Fill a wide pot with ~1 1/2 inches water, add a ring of crumpled foil to the pot (this is to raise the mixing bowl off the bottom). Bring to a boil then adjust temperature to maintain a gentle simmer.
Combine egg whites, sugar, salt, and cream of tartar in the bowl of a stand mixer. Set over the steaming water, stirring and scraping with a flexible spatula, until egg whites reach 185°F. This should take only 10 to 12 minutes,
Transfer the bowl to a stand mixer. Whip on high speed using the whisk attachment until meringue is glossy, stiff, and cool to the touch. This should take about 10 minutes.
With mixer still running, add butter, 1 or 2 tablespoons at a time. In the end, the buttercream should be thick, creamy, and soft but not runny.
Melt chocolate until just melted enough to stir until smooth. (I do this in a pyrex measuring cup in the microwave, but you can also use a double boiler)
Scrape all of the warm chocolate into stand mixer bowl at once, then immediately begin whipping on medium-high until fully incorporated.
Mix in Kahlua and espresso until well combined.
Use buttercream right away, or transfer to a large ziploc bag, press out air, and seal. Buttercream can be refrigerated for up to 2 weeks and frozen for up to several months.
Frost cooled layers with buttercream. I kept it to the two layers, but you could also split the layers horizontally to create a 4 layer cake…this gives you more frosting per bite, which is never a bad thing IMO!
Pipe large rosettes with an oversize star tip around edges of top and garnish with chocolate covered espresso beans if desired.
Mocha is one of my favorite flavors, and this may be the best cake I have ever made. What a divine combination this makes! The chocolate cake layers are melt in your mouth moist but still cake-like. And Swiss buttercream is the food of the gods!
Someday, in the not too distant future, I’m going to host a buttercream tasting. Like a wine tasting, only with the different buttercream types atop mini cupcakes and labeled by anonymous number to be rated by the guests! It will be the battle of the buttercreams!
