Devil's Food Cake with Fudge Frosting

1/2 cup plus 2 tbls. unsweetened American-style cocoa powder (not Dutch process), plus more for dusting

2/3 cup boiling water

1 1/2 tsps. baking soda

4 ozs. unsweetened chocolate, coarsely chopped or broken into small pieces

2 cups plus 2 tbls. cake flour

1/2 tsp. baking powder

Generous 1/4 tsp. salt

2 1/2 sticks unsalted butter, slightly softened

2 1/2 cups sugar, divided

1 large whole egg

5 large egg yolks

1 cup sour cream

1 tbl. pure vanilla extract

4 large egg whites

Fudge Frosting (recipe follows)

1. Preheat oven to 350 degrees and position a rack in the center. Grease 3 (9-inch) round cake pans very generously. Line the bottoms of the pans with waxed paper. Grease the paper. Dust the pans generously with cocoa powder, tapping out any excess.

2. In a medium bowl, pour the boiling water over the 1/2 cup plus 2 tablespoons cocoa powder and stir until completely smooth. Stir in the baking soda until well blended. Let the mixture cool.

3. In a double boiler, melt the chocolate over 1 inch of hot, but not simmering water, stirring occasionally, about 5 minutes. Remove the pan from heat and set aside.

4. Sift together the flour, baking powder and salt. Set aside.

5. Put the butter in the large bowl of a standing electric mixer and beat at medium speed until very light and fluffy, about 2 minutes. Add 21/4 cups of the sugar and beat until well blended, about 3 minutes.

6. Beat in the whole egg and the egg yolks, 1 at a time. Then beat in the cooled cocoa mixture until very smooth. Beat in the slightly warm chocolate mixture until evenly incorporated.

7. At low speed, beat in half of the dry ingredients, then the sour cream and vanilla, then the remaining half of the dry ingredients, just until evenly incorporated and smooth.

8. In a completely grease-free large bowl of an electric mixer, beat the egg whites at medium speed until foamy and opaque. Increase the speed to high and continue beating until soft peaks begin to form. Gradually beat in the remaining 1/4 cup of sugar and beat until the peaks are stiff but not dry.

9. Using a rubber spatula or whisk, fold about 1 cup of the chocolate batter into the whites. Then gently fold the whites into the remaining batter until thoroughly incorporated. Do not overmix.

10. Divide the batter equally among the prepared pans, spreading it to the edges with a rubber spatula. Bake on 2 oven racks for 30-35 minutes or until a cake tester inserted in the center comes out clean, but still moist, the top springs back slightly when lightly pressed and the layers are pulling away from the sides of the pans. Transfer the pans to racks and let cool completely.

11. Carefully run a thin knife around the edges of the pans to loosen the cake layers. Rap the pans sharply and repeatedly against the counter top until the layers loosen. Invert each layer onto a flat plate or board. Peel off waxed paper. Lay a cooling rack on each cake bottom and invert so that cakes are right side up.

12. Place 1 cake layer on a serving platter. Using an icing spatula or a table knife, immediately spread a generous fourth of the Fudge Frosting on the layer. Place another cake layer on top and spread on another generous fourth of the frosting. Add the final layer.

13. Cover the top and sides of the cake evenly with the remaining Fudge Frosting, smoothing or swirling it attractively. Let stand a few minutes until frosting firms slightly, then serve.

FUDGE FROSTING

1 1/4 cups heavy cream

1 2/3 cups sugar

6 1/2 ozs. unsweetened chocolate, finely chopped

1 1/2 sticks cold, unsalted butter, cut into 12 tablespoons

1 1/2 tsps. pure vanilla extract

1. In a medium saucepan, stir together the heavy cream and the sugar. Bring to a boil over moderately high heat, stirring once or twice. Reduce the heat to moderately low and cook, stirring occasionally, until the mixture thickens slightly, about 4 minutes. Adjust the heat to maintain a simmer and cook, stirring often, for 2 minutes longer. Remove from heat.

2. In a large bowl, combine the chocolate and the butter. Pour in the hot cream and stir occasionally with a wooden spoon until completely melted. Stir in the vanilla just until blended.

3. Place the bowl in a larger bowl filled with ice water. Using a hand-held mixer, beat the frosting at high speed until shiny and thick enough to hold a shape, about 5 minutes. Watch carefully as you beat. If the frosting near the side of the bowl becomes very stiff, immediately remove the bowl of frosting from the ice bath and continue beating.