Preheat the oven to 350 degrees. Butter two 8-inch round cake pans. Line with parchment paper, then butter and flour the pans.
Sift the flour, sugar, cocoa, baking soda, baking powder, and salt into the bowl of an electric mixer fitted with the paddle attachment and mix on low speed until combined. In another bowl, combine the buttermilk, oil, eggs, and vanilla. With the mixer on low speed, slowly add the wet ingredients to the dry ones. With mixer still on low, add the coffee and stir just to combine, scraping the bottom of the bowl with a rubber spatula. Pour the batter evenly into the prepared pans and bake for 35 to 40 minutes, until a cake tester comes out clean. Cool in the pans for 30 minutes, then turn them out onto a cooling rack and cool completely. (Not to worry; the top will sink a little in the center.)
Place one layer, flat side up, on a flat plate or cake pedestal. With a knife or offset spatula, spread a thin layer of buttercream on the top only. Place the second layer on top, flat side up, and spread the frosting evenly first on the sides and then on the top of the cake. Cut in wedges and serve at room temperature.
Chocolate Buttercream Frosting
Chop the chocolate and place it in a heatproof bowl over a pan over simmering water. Stir until just melted and set aside until cooled to room temperature.
Beat the butter in the bowl of an electric mixer fitted with the paddle attachment on medium-high speed until light yellow and fluffy, about 3 minutes. Add the egg yolk and vanilla and continue beating for 3 minutes. Turn the mixer to low, gradually add the confectioners’ sugar, then beat at medium speed, scraping down the bowl as necessary, until smooth and creamy. Dissolve the coffee in 2 teaspoons of the hottest tap water. On low speed, add the chocolate and coffee to the butter mixture and mix until blended. Don’t whip! Spread immediately on the cooled cake.
Note: I use Valrhona Le Noir 56% Cacao Semisweet Chocolate. You can use also use a good bittersweet chocolate but don’t use chocolate chips because they have stabilizers in them.
Copyright 2006, Barefoot Contessa at Home by Ina Garten, Clarkson Potter/Publishers, All Rights Reserved