1packagered jumbo hearts (from Wilton) or make your own using red melting candies
Melt butter in large sauce pan over low heat then add the food coloring and stir. Add the marshmallows next. Stir constantly until melted and completely blended. Remove mixture from heat.
Immediately add cereal. Stir until well coated.
Using buttered spatula or waxed paper, press mixture evenly and firmly in buttered 8x8 inch pan. Add heart sprinkles or sprinkles of choice. Cut into squares when cool and then add an icing heart using the red icing OR (updated) use a large red heart decoration.
If the decoration does not stick very well... just add a dab of icing or red melting candy to the back side to affix to the Rice Krispie treat. If using the icing: leave it to dry for an hour and the hearts will not be too sticky to the touch.