1. Heat oven to 350°F. Grease and flour two 9-inch round baking pans.
2. Stir together sugar, flour, cocoa, baking powder, baking soda and salt in large bowl. Add eggs, milk, oil and vanilla; beat on medium speed of mixer 2 minutes. Stir in boiling water (batter will be thin). Pour batter into prepared pans.
3. Bake 30 to 35 minutes or until wooden pick inserted in center comes out clean. Cool 10 minutes; remove from pans to wire rack. Cool completely.
4. Tint frosting to desired shade of pink with several drops red food color. Frost cake.
5. Cut desired size heart from wax paper. Lightly place on surface of cake (do not press into cake); use edge of knife or toothpick to outline heart onto frosted cake surface. Remove paper. Place mini peanut butter cups on cake following heart outline. Makes 12 servings.