Heavenly Heart Cake

Heat oven to 350°F (175°C). Grease and flour 2 heart-shaped pans or two 9-inch round baking pans. Stir together cocoa and boiling water in small bowl until smooth; set aside. Beat butter, sugar and vanilla in large bowl until fluffy; beat in eggs and cocoa mixture. Stir together flour, baking soda and salt; add alternately with buttermilk to butter mixture. Pour batter into prepared pans. Bake 30 to 35 minutes or until wooden pick inserted in center comes out clean. Cool 10 minutes; remove from pans to wire racks. Cool completely. Frost with GLOSSY CHOCOLATE SOUR CREAM FROSTING. Pipe border around top edge and base of cake with CREAMY BUTTERCREAM FROSTING. Garnish as desired. Place small chocolate chips in medium microwave-safe bowl. Microwave at HIGH (100%) 1 minute; stir. If necessary, microwave at HIGH an additional 15 seconds at a time, stirring after each heating, just until chips are melted when stirred. Add powdered sugar, sour cream and vanilla; beat until smooth. Add milk, 1/2 teaspoon at a time, for a thinner consistency.