In a 1 quart microwave safe bowl, heat chocolate chips, peanut butter, and butter for 1 minute on high heat. Stir. Microwave 30 seconds longer or until melted and smooth. Stir in vanilla.
Pour chocolate mixture over cereal and stir well to coat all pieces. Add powdered sugar and stir until completely coated. Spread out on waxed paper or foil for about 30 minutes. Or 5 minutes. Whatever :) Store in an airtight container at room temp, or in the fridge.