Heat oven to 350F. Grease and flour rectangular pan, 13 x 9 x 2-inches; 3 round pans, 8 x 1 1/2 inches; or 2 round pans, 9 x 1 1/2 inches. Beat all ingredients except Fudge Frosting in large bowl on low speed 30 seconds, scraping bowl constantly. Beat on high speed 3 minutes, scraping bowl occasionally. Pour into pans. Bake rectangular pan 40 to 45 minutes, round pans 30 to 35 minutes or until wooden pick inserted in center comes out clean. Cool rounds 10 minutes; remove from pans. Cool completely. Prepare Fudge Frosting; frost cake. (Fill layers with 1/3 cup frosting; frost side and top with remaining frosting.) FUDGE FROSTING Mix all ingredients except vanilla in 2 1/2-quart saucepan. Heat to rolling boil, stirring occasionally. Boil 1 minute without stirring. Place saucepan in bowl of ice and water. Beat until frosting is smooth and of spreading consistency; stir in vanilla.