In a large saucepan, melt the butter over low heat. Add the marshmallows and stir continuously until completely smooth. Remove from heat.

Stir in the Rice Krispies cereal until completely coated.

Turn the mixture out onto a large sheet of parchment paper or wax paper. Using a greased spatula, shape it into a large rectangle, keeping it about an inch deep all over.

Grease a 3-inch heart shaped cookie cutter and cut out the hearts. Once you've made the first round of cuts, reshape the remaining rice krispie mixture into another smaller square or rectangle and repeat until you've cut all the hearts.

Let the hearts harden for about 15 minutes while you melt the chocolate in a double boiler or microwave safe bowl' (at half power for 30 seconds, and then 15-second intervals until smooth). Dip the treats into the chocolate, or drizzle the chocolate, and add sprinkles. Harden in the fridge for about 10 minutes or just until the chocolate is set. Enjoy!