Melt your chocolate in a microwave or stovetop. Whisk in the peanut butter until smooth. Pour the chocolate/peanut butter mixture over the cereal and mix very well, until combined.
Transfer the mixture into a lined baking dish. Add the powdered sugar over it, and mix until the cereal is mostly covered. Gently mix it, before allowing the chocolate to cool completely.
Transfer into a large mixing bowl and serve immediately.
Video
Notes
TO STORE: Puppy chow can be stored at room temperature, covered. It will keep well for up to 4 weeks. TO FREEZE: Place the puppy chow in a ziplock bag and store it in the freezer for up to 6 months.