Preheat oven to 350 degrees. Grease and flour 3 (9 inch) layer cake pans. Cream the butter and sugar well. Add vanilla and egg yolks; beat well. Sift the dry ingredients together and add to mixture, alternating with buttermilk and coffee. Beat egg whites until stiff. Pour into prepared cake pans. Bake at 350 degrees for 30 minutes. When cake is cool enough not to melt icing, stack layers.
Cream butter and sugar. Add egg yolk, vanilla, cocoa and coffee. Beat well. Spread between layers, top and sides of cake.