Line a 9x13 baking dish with foil and spray with non stick cooking spray.
Heat the 3 tablespoons of butter and 10 oz of mini marshmallows in a large saucepan or dutch oven, stirring occasionally.
Once the marshmallows are melted, pour in the 6 cups of Rice Krispie cereal. Gently fold the cereal into the melted marshmallows and pour the Rice Krispie treats into the prepared baking dish and evenly press into the pan (use wax paper to press down the mix - this will help avoid sticking to your hands) and set aside.
In a small bowl, combine powdered sugar, 1/3 cup melted butter and vanilla extract and a tablespoon of milk. Once the frosting has reached your desired consistency, add in a few drops of pink food coloring and stir to combine.
Attach the small round frosting tip to the disposable piping bag and fill with frosting.
Use the heart cookie cutter to cut the Rice Krispie treats as close together as possible getting an many as you can.
Take one Rice Krispie heart at a time and place one toothpick on each side so it looks like an arrow coming out from each side.
Stick one gummy heart candy on one toothpick.
Take a second heart and use the kitchen scissors to snip a triangle out of the top. Place this heart on the other toothpick.
Gently squeeze the frosting out onto the heart treat in a back and forth motion.