Grease two 9-inch or three 8-inch-round baking pans. Line bottoms with waxed paper. Grease paper; flour.
Beat ingredients in bowl on low until blended. Beat on high 3 minutes. Scrape into pans.
Bake in preheated 350 degree F oven 30 to 35 minutes or until wooden pick tests clean. Cool pans on racks 5 minutes. Unmold cakes; cool.
Beat ingredients in bowl until smooth spreading consistency.
Beat butter and chocolate in bowl. Stir in vanilla and sugar; add enough milk for spreading consistency; beat until smooth.
Stack layers with filling; spread top with filling; use all filling. Frost sides of cake. Garnish with peanuts. Makes 16 servings.