In large bowl, place cereal. In small microwavable bowl, microwave baking chips, peanut butter and butter uncovered on High 1 minute to 1 minute 30 seconds, stirring every 30 seconds, until melted and smooth. Pour peanut butter mixture over cereal, stirring until evenly coated.
Place 1/2 of the cereal mixture in 1-gallon food-storage plastic bag. Add powdered sugar. Seal bag; shake until well coated. Spread on waxed paper or foil to cool, about 15 minutes.
Meanwhile, stir candies and sprinkles into remaining cereal mixture. Spread on waxed paper or foil to cool, about 15 minutes.
In serving bowl, mix both cereal mixtures. Store in airtight container.