for the COCOA SPONGE CAKE:
1 teaspoon unsalted butter
1 teaspoon all purpose flour
4 egg whites
1/2 cup sugar
4 egg yolks
1/2 cup all purpose flour sifted together with 1/4 cup cocoa powder
for the cocoa syrup:
1/4 cup sugar
1 1/2 teaspoons cocoa powder
for the chocolate mousse filling:
10 ounces bittersweet chocolate
2 cups heavy cream, whipped until stiff
1/2 cups sliced almonds, toasted
3 ounces chocolate for curls
the cocoa sponge cake:
Preheat oven at 350 degrees. Butter and flour an 8-inch springform pan. With an electric mixer, beat the egg whites, slowly adding the sugar, and continue to whip until stiff.
Beat in the egg yolks, then gradually fold in the flour sifted together with cocoa powder. Pour the batter into the cake mold and bake for 15 to 18 minutes Remove from heat and unmold on a pastry rack to cool.
For the cocoa syrup:
Bring 1/4 cup of water, sugar, and cocoa powder to a boil in a small pot. Remove from heat and set aside.
For the chocolate mousse filling:
Melt the chocolate in the top of a double boiler. Cool until warm to touch. Fold in the whipped cream until smooth.
Place the cake on a round cake circle.
Split the cake horizontally into 2 equal disks with a serrated knife. Brush the bottom disk with half of the cocoa syrup.
Spread half of the chocolate filling over the cake, then sprinkle with half of the almonds. Cover with the top disk.
Repeat the same process with the syrup, filling, spreading some filling around the sides.
Decorate the sides with almonds, and the top with chocolate curls.