Spray a 9 x 13 pan with cooking spray. In a large saucepan combine the butter and marshmallows. Cook over medium heat, mixing frequently, until the marshmallow are melted.
Add the salt and food coloring and mix well. Remove from heat. Add the Rice Krispies and mix well to combine. Spread the treats into the prepared pan and press to flatten.
Allow the treats to harden for 30 minutes. Using a heart cookie cutter cut heart shapes out of the treats. Place the hearts on waxed paper or parchment paper.
Place red candy melts in a microwave safe bowl. Heat for 30 seconds and stir. Continue heating in 15 second intervals, stirring after each heating, until melted.