June 12, 2015
Because the only thing better than melted chocolate is combining that chocolate with a fresh, juicy strawberry.
3 hrs 25 mins
To Make the Chocolate Cake:
Add the butter and both sugars to the bowl of a large stand mixer fitted with a paddle attachment. Beat them together on medium-high speed, until light and fluffy, about 5 minutes. Add the eggs one at a time, beating well after each addition. Add the vanilla extract and mix it in.
In a separate bowl, whisk together the buttermilk, sour cream, and water (or coffee, if using). In a different bowl, sift together the flour, cocoa powder, baking soda, and salt. With the mixer running on low, add a quarter of the sifted flour mixture. When the flour streaks have almost all disappeared, add a third of the liquid to the mixing bowl. When that’s incorporated, continue to add the drys and wets in an alternating pattern, ending with the dry ingredients.
When the dry ingredients are nearly incorporated, stop the mixer. Scrape down the bottom and sides of the bowl with a rubber spatula, and finish mixing the cake by hand. Pour the batter into the prepared pan and smooth it into an even layer.
Bake the cake for 20-25 minutes, until a toothpick inserted into the center comes out with just a few moist crumbs attached. Cool the cake completely before using. The cake can be made several days in advance and kept, well-wrapped and refrigerated or frozen, until ready to use. If you freeze it, make sure it's partially defrosted before you use it so you can cut it easily.
For the Strawberry Buttercream:
Combine the egg whites and the granulated sugar in the bowl of a large stand mixer, and whisk them together. Choose a small saucepan that lets you fit the base of the stand mixer snugly into the top of the saucepan—this is your makeshift hot water bath. (Alternately, you can use a different bowl or an actual bain marie and then transfer the mixture to a mixing bowl once it’s heated.) Add an inch of water to the bottom of the saucepan, and bring the water to a simmer.
Place the mixing bowl on top of the saucepan, making sure that the bottom isn’t in contact with the water, and heat the egg white mixture. Whisk frequently so that the egg whites don’t cook. Continue to heat the whites until they are hot to the touch, and when you rub a bit between your fingers, you don’t feel any grittiness from the sugar. Once the whites are hot, transfer the mixing bowl to your mixer and fit it with a whisk attachment.
Beat the whites on medium-high speed until they are a shiny, stiff, voluminous meringue, and are no longer warm to the touch—feel the outside of the bowl, and make sure that it is around room temperature. Depending on your mixer and the temperature of your environment, this may take 15-20 minutes, or more. Reduce the speed to medium-low and add the softened but cool butter in small chunks, a tablespoon at a time, making sure to wait in between additions. It may separate or look a little gloopy at this point—fear not. Once all of the butter is added, increase the speed again and whip until it comes together and is light and fluffy. If, after 5 minutes, it hasn’t come together, refrigerate the mixing bowl for 5-7 minutes, to cool the mixture down, and whip it again until it has thickened and is smooth and silky.
With the mixer running, slowly add the strawberry puree in batches, letting it incorporate little by little. Adding it slowly will help prevent it from separating from the addition of the extra liquid. Once all of the puree is added, add a few drops of pink food coloring until you get a color you like.
The buttercream can be made in advance and kept at room temperature if you’re going to use it the same day, or refrigerated. If it has been chilled, let it sit at room temperature until completely soft, then re-whip it to get the smooth texture back before you use it.
For the Chocolate Ganache:
Place the chopped semi-sweet chocolate in a medium bowl and set aside. Pour the heavy cream into a small saucepan and place it over medium heat. Bring it to a simmer so that bubbles appear along the sides of the pan, but don't let it boil.
Pour the hot cream over the chopped chocolate and let it sit for one minute to soften and melt the chocolate. After a minute, gently whisk the cream and chocolate together until it is shiny and smooth. If you won't be using it soon after making it, press a layer of cling wrap on top of the chocolate and refrigerate it for up to a week. To use it, gently re-warm it in short intervals in the microwave, whisking frequently, until it is fluid again.
Use a 3½-inch round cutter to cut 15 circles from the half-sheet cake. Space them as close together as you can, and don’t worry if an edge or two is not exactly round—that can all be smoothed over with frosting later.
Wash and dry the 2 cups of strawberries. Hull them and chop them finely. Cut out five cardboard rounds the same size as your cake circles, and place a cake circle on each round. Spread a layer of frosting on top of one of the cake layers on a cardboard circle, and use an offset spatula to spread it out to the edge. Sprinkle some of the chopped strawberries on top, and press them down gently to embed them in the frosting. Top it with a second cake slice, then add a layer of frosting on top of that. Finally, finish it off with a third cake slice. Spread a very thin layer of frosting on the top and sides of the cake. This is the "crumb coat" and is just used to lock in any stray crumbs. Repeat until you have assembled 5 mini cakes. Place the cakes on a baking sheet and refrigerate them for at least an hour, until the crumb coat is very firm.
Re-whip the frosting if necessary, so that it is very smooth and not spongy. Add a thicker layer of frosting to the top and sides of the cake, covering the crumb coat, making sure the frosting is as smooth as possible. To get the sides extra-smooth, run a metal offset spatula under very hot water, then wipe it dry and run it along the sides of the cake—the heat from the spatula helps smooth out the frosting. Repeat until all of the mini cakes have a final layer of frosting on them, then refrigerate them again to set the frosting.
Re-warm the ganache, if necessary, until it flows easily. Transfer it to a measuring cup with a spout, and pour some on top of a cake, until it goes almost out to the edge. Use a spatula to nudge around the sides of the cake, encouraging drips to go down the sides, until you've gone around the whole cake. Repeat until all of the cakes have a coating of drippy ganache.
If you want your chocolate-dipped strawberries to stand upright on top of the cakes, insert a wooden skewer going all the way to the bottom of the cake and extending about ¾-inch up above the surface.
Make sure your strawberries are washed and completely dry. Dip a strawberry in the ganache until it is nearly covered, then remove it and let excess drip back into the pan. Prop it up on top of the cake, resting the back on the wooden skewer so that it balances upright. Repeat until all of the cakes are topped with chocolate-dipped strawberries.
For the Chocolate Cake:
For the Strawberry Buttercream:
For the Chocolate Ganache and Assembly: