Heat treat the brownie mix

• Microwave the brownie mix in 30-second intervals until it reaches 165 °F, or bake it at 350 °F for 3–5 minutes.
• Let it cool completely.

Melt the chocolate mixture

• Melt the milk chocolate chips, peanut butter and butter together until smooth.
• Stir in the marshmallow fluff.

Coat the cereal

• Pour the chocolate mixture over the Rice Chex and Chocolate Cheerios.
• Gently stir until the cereal is evenly coated.

Shake with the sugar coating

• Combine the powdered sugar and heat-treated brownie mix in a large zip-top bag or container.
• Add the coated cereal and shake until well coated.

Cool

• Spread the puppy chow out on a tray and let it cool.

Finish and serve

• Mix in the mini marshmallows, spooky sprinkles and Halloween M&M's.
• Top with a few extra sprinkles if you like.