Line a 9x9 inch tin with parchment paper, set aside.
Add the marshmallows and butter to a large bowl then microwave for 2-3 minutes until the marshmallows are melted into the butter
Working quickly, fold the rice krispies into the melted marshmallow mixture.
Transfer the mixture to the prepared tin then press town into one even layer.
Allow to set at room temperature for a minimum of 2 hours to over night.
Once set, use a heart shaped cookie cutter to cut out heart shaped rice krispie treats.
Once all of the hearts have been cut out, decorate the rim of each heart with the icing. Lastly, write “xoxo” of “Luv you” in the center of each heart.