Unwrap BUTTERFINGER® bars, place in a zip-top bag, and crush each candy with a mallet or similar, once until it breaks the candies in to large pieces. Pour crushed candies over cereal. Keep in mind, you'll still want the candies big enough to pick up with your fingers when eating the puppy chow.
In a microwave safe bowl, combine chocolate chips, peanut butter, and butter. Microwave for 1 minute, and stir. If chips are not completely melted, place back in microwave for 30-second intervals until completely melted.
Stir in vanilla extract.
Pour chocolate mixture over cereal/candy mixture.
Stir gently until cereal is evenly coated, being careful not to break too many pieces of the cereal and candy.
Once coated, sprinkle half of the powdered sugar on top of the cereal/chocolate mixture. Stir gently until evenly distributed.
Pour remaining powdered sugar over the mixture, stirring until evenly coated.
Store in an airtight container until ready to serve!