1. Place cereal in a large bowl and set aside. In a medium microwavable bowl, add chocolate chips, peanut butter and butter. Microwave on High for 1 minute and stir. Microwave 30 seconds longer and stir mixture until smooth. Stir in vanilla. Pour sauce over cereal and stir until evenly coated. Spoon half of the mixture in each 1-gallon resealable ziplock bag. Add 3/4 cup powdered sugar to each bag, and seal. Shake the bag until everything is coated. Spread on waxed/parchment paper to cool. Store in airtight container in refrigerator.