PREPARE and bake cake mix as directed on package, dividing batter evenly between 8-inch square cake pan and 8-inch round cake pan. Cool completely. CUT round cake in half. Leave square cake whole. Place square cake on serving tray in diamond position. Using small amount of whipped topping to hold pieces together, place half circles against top 2 adjacent sides of square cake to create "heart." FROST cake with remaining whipped topping. Tint coconut pink with red food coloring; sprinkle over frosting. Decorate with assorted heart-shaped candies, if desired. Store leftover cake in refrigerator.