Almonds; whole, blanched Chocolate garnishes, optional Position rack in center of oven and preheat to 350 degrees. Cover bases of two 9" springform pans with foil, then attach sides. Finely grind almonds with 4 tbsp sugar. Sift flour, cocoa, baking powder into a small bowl. Stir in almond mixture. Beat yolks and 8 tbsp sugar using electric mixer until slowly dissolving ribbons form when beaters are lifted, about 6 minutes. Beat whites in another bowl, with cream of tartar until stiff but not dry. Gradually, add remaining 4 tbsp of sugar and beat until whites are stiff and shiny. Fold 1/3 of almond/cocoa mixture into yolks, then 1/3 of egg whites. Repeat twice, folding in melted butter just before final 1/3 of whites is incorporated. Spoon 1/2 of batter into each pan, smoothing surface with spatula. Bake until tester inserted in center of cake comes out dry, about 20 minutes. Cool in pans on rack 5 minutes. Invert onto rack and cool cakes completely. Melt chocolate in top of double boiler over hot, but not boiling water. Bring milk to simmer in heavy medium saucepan over low heat. Whisk yolks and sugar in bowl until smooth. Gradually, whisk in hot milk, return to saucepan. Stir over low heat until mixture leaves path on back of spoon when finger is drawn across it, about 5 to 7 minutes. Do Not Boil. Gradually, whisk custard into chocolate until smooth. Cool completely, stirring occasionally. Whip cream to soft peaks. Fold into cooled chocolate mixture in 3 batches. To assemble, cut each cake into 2 layers, using a serrated knife. Set one layer, cut side up in the 9" springform pan. Combine liqueur and water. Brush 4 tbsp onto cake in pan. Spoon 1/4 of chocolate parfait over cake, spreading to edge. Top with second layer, cut side up. Repeat with liqueur and parfait. Add third layer and repeat. Add forth layer and repeat, smoothing top of parfait with a spatula. Cover and freeze until firm, at least 4 hours. Remove pan sides. Refrigerate cake while preparing cream. Melt chocolate in double boiler over hot, but not boiling water. Stir until smooth. Remove from over water. Whip cream with sugar and vanilla to stiff peaks. Whisk in chocolate. Spoon mixture into a pastry bag fitted with medium star tip. Set cake on serving platter. Pipe decorative whipped cream rosettes around edge of cake. Set almonds in rosettes. May also use chocolate leaves or curls as garnish.