Cake
1/3 cup flour
1/4 cup cocoa
1/4 teaspoon baking soda
4 egg yolks
1/2 teaspoon vanilla extract
1/3 cup sugar
4 egg whites
1/2 cup sugar
Custard
4 beaten egg yolks
2 cups milk
1/4 cup sugar
1 tablespoon Amaretto
Filling
1/3 cup seedless raspberry jam
1/4 cup Amaretto
2 cups fresh or frozen raspberries, thawed and drained if necessary
1/4 cup toasted slivered almonds
4 ounces chopped bittersweet chocolate
1/3 cup heavy whipping cream
1/2 teaspoon cocoa

Cake
Heat oven to 375°F. Grease and lightly flour a 15x10 inch jelly roll pan. Stir together flour, cocoa and baking soda and set aside. Beat 4 egg yolks and vanilla together till thick and lemon-colored. Gradually add sugar and beat on high till sugar is almost dissolved. Beat egg whites till soft peaks form. Gradually add sugar, beating till stiff peaks form. Fold egg yolk mixture into beaten egg whites. Sprinkle flour mixture over egg mixture and fold in gently just till combined. Spread batter evenly in prepared pan. Bake for 15-18 minutes till cake springs back when lightly touched. Immediately loosen edges of cake from pan and turn cake out onto a rack. Cool completely.
Custard
Combine egg yolks, milk and sugar in a heavy medium saucepan. Cook and stir over medium heat till mixture just coats a metal spoon. Remove pan from heat and stir in Amaretto. Quickly cool by placing the saucepan in a pan of ice water for 1-2 minutes, stirring constantly. Pour custard mixture into a bowl. Cover the surface with plastic wrap. Chill for 1-4 hours.
Filling
To assemble trifle, spread raspberry jam over top of chocolate sponge cake. Cut cake into 18 rectangles. Arrange half of the rectangles, preserves side up, on bottom of a 2 1/2 quart glass bowl. Sprinkle with Amaretto. Sprinkle with half of the raspberries and half of the almonds. Spread half of the custard over all. Sprinkle with half of chopped chocolate. Repeat layers. Cover and chill for 3-8 hours. Beat cream till stiff peaks form. Dollop onto trifle. Sift cocoa over top of trifle.