Cut the ½ cup salted butter into slices and put in an extra large microwave safe bowl. Add the 20 ounces mini marshmallows.
Microwave for a minute and a half. Stir until no chunks of marshmallow or butter are visible. If it isn't completely smooth, microwave for another 10-20 seconds until everything is melted when you stir it.
Add the 18.8 ounces Cinnamon Toast Crunch to the bowl. Quickly, but gently, stir to coat the cereal in the marshmallow.
Transfer the mixture to the greased pan and press to make an even layer. If you grease your hand or spatula before spreading the mixture, it makes it a little bit easier and less sticky.
Allow to set at room temperature for an hour before cutting and serving.
Notes
This recipe makes nice thick bars. For thinner bars, just cut it in half.These treats should be stored in an airtight container at room temperature. Don't refrigerate or freeze as it will affect the texture.