Bake and cool cake. Prepare batter following recipe directions. Place bakeware on cookie sheet. Bake and cool cakes following package directions.
Decorate cake. Prepare buttercream icing following recipe directions. Use rose icing color to tint icing pink. Use 9 inch angled spatula and pink icing to ice top of cake smooth.
Use 9 in. fondant roller with purple guide rings to roll out white fondant 1/16 in. thick. Use medium cut-out from set to cut heart. Place white heart on the center of cake. Roll out red fondant 1/16 inch thick. Use small cut-out from set to cut heart. Brush red heart with damp brush to secure to the center of white heart.