Vanilla buttercream frosting: Beat 1 (16 ounces) package powdered sugar, half cup butter, 3 tablespoons milk, and 2 teaspoons vanilla with a mixer on low until well blended and smooth. Sweet heart cake: Tint buttercream frosting pink using red food coloring. Tint coconut pink using red food coloring. Leave square cake whole. Cut round cake in half. Using a small amount of frosting to hold pieces together, arrange cake on serving tray with one half round cake on one flat side of square cake, repeating process, at right angles of square cake thus making a heart. Frost cake over all with remaining frosting. Sprinkle with coconut. Flatten red and white gumdrops with rolling pin. Cut into 5 cm heart shapes with a small cookie cutter or knife. Decorate center of cake with heart cut-outs. Cut fruit snack roll, flattened out, into strips. Make a bow and place with hearts in center of cake.