Separate eggs. Allow egg yolks and egg whites to stand at room temperature for 30 minutes. Grease the bottoms of three 9 x1-1/2-inch round cake pans. Line pans with waxed paper; grease waxed paper. Set pans aside. In a medium bowl, stir together flour and baking powder; set aside.

In a large mixing bowl, beat egg yolks, sugar and coffee with an electric mixer on low speed until combined. Beat on high speed about 5 minutes or until satin smooth. Add flour mixture and beat until combined; stir in nuts. Set aside.

Thoroughly wash beaters. In a very large mixing bowl, beat egg whites on medium speed until stiff peaks form (tips stand straight). Gradually fold batter into beaten egg whites until combined. Pour into prepared baking pans.

Bake in a 350 degrees oven for 20 to 25 minutes or until cake tops spring back when lightly touched (centers may dip slightly). Cool cake layers on wire racks for 10 minutes. Remove cake layers from pans; remove waxed paper. Cool thoroughly on wire racks. Spread 1/2 cup Creamy Butter Frosting on each layer; stack layers. Frost sides of cake with remaining frosting. If you like, garnish with chopped nuts. Loosely cover and chill cake for up to 3 days. Serves 12 to 14.

In a small saucepan, whisk 1/2 cup milk into 2 teaspoons cornstarch. Cook and stir over medium heat until thickened and bubbly. Reduce heat; cook and stir for 2 minutes more. If you like, stir in 1 tablespoon rum or 1/2 teaspoon rum extract. Cover surface with plastic wrap. Cool to room temperature (do not stir). In a large mixing bowl, beat 3/4 cup softened butter for 30 seconds. Add 2 cups powdered sugar; 2 tablespoons unsweetened cocoa powder, if you like; and 1 teaspoon vanilla. Beat with electric mixer on medium speed until light and fluffy. Add cooled milk mixture to butter mixture, half at a time, beating on low speed after each addition until smooth. Beat in 5 to 6 cups additional powdered sugar until spreading consistency. Makes about 3-1/4 cups frosting.