In a large pot, melt butter and marshmallows over low heat, stirring occasionally.
Remove from heat, stir in vanilla extract.
Add the cereal to the marshmallow mixture, stir to coat evenly.
Spread cereal mixture in an even layer into a greased 13x9 inch pan and allow to cool.
While the Rice Krispie treats cool, place white chocolate chips into a microwave-safe bowl.
Microwave chocolate chips about 1 minute or until fully melted.
Carefully remove cooled treats from pan and place onto a cutting board. Cut out shapes with a heart shaped cookie cutter.
Dip one side of the Rice Krispie hearts into the chocolate, place on parchment paper, then sprinkle with sprinkles.
Allow chocolate to cool and harden before enjoying.
Notes
Use fresh marshmallows for the best texture. Stale or hardened marshmallows can affect the gooey consistency of the treats.
Large marshmallows can be used for this recipe as well, you'll need a 10 ounce bag.
While the recipe calls for salted butter, feel free to use unsalted butter if that's what you have on hand.
Create an even layer of Rice Krispies in the baking pan by spraying a rubber spatula with cooking spray or using a piece of wax paper. This simple trick ensures a smooth and uniform base before cutting out your heart shapes.
Lightly grease the cookie cutter with cooking spray or butter to prevent sticking when cutting out the heart shapes.
Allow the treats to set in the refrigerator for a faster and firmer result. This also helps the white chocolate coating to harden, making them easier to handle.