Spray a 9x13 baking dish with nonstick cooking spray. Pour the mini chocolate chips into the bottom of the pan.

In a large pan, melt the butter over low heat. Add the marshmallows and stir until melted. Remove from heat and stir in Rice Krispies. Continue stirring until the cereal is well coated with the marshmallow mixture. Spread into the bottom of the prepared dish and press down. Let sit for about an hour until cooled.