How do You Make Puppy Chow?

The ingredients for Puppy Chow are 1/2 cup Peanut Butter, 1/4 cup Butter, 1 cup chocolate chips, 1/2 tsp vanilla, 9 cups Crispix or Chex cereal, and 1 1/2 cups of powdered sugar. Mix the ingredients other than the cereal together and microwave until melted. Pour over the cereal and mix well, then coat with the powdered sugar.