Combine peanut butter, butter, and chocolate chips in a microwavable bowl.
Microwave for 1 minute, then stir until melted and creamy. Add vanilla and stir. In a large bowl with a cover, pour chocolate mixture over cereal.
Cover and shake until cereal is evenly coated. Sprinkle powdered sugar over cereal. Cover and shake until evenly coated. Add M&Ms and sprinkles of your choice.