Combine peanut butter, butter, chocolate chips and butterscotch chips in a double broiler melt over medium-low heat
Stir in vanilla
Place the 9 cups of Chex cereal in a very large bowl
Pour the peanut butter-chocolate mixture over the cereal and toss, until all the cereal is coated
Place the powdered sugar in a large zip-lock bag
Add the peanut butter-chocolate cereal mixture to the bag, leaving enough room for the puppy chow to be shaken (you may have to divide the mixture into smaller batches, coating one batch at a time).
Shake the bag to coat each piece of the puppy chow with powdered sugar.
Once the mixture is fully coated, place in a large serving bowl and serve
