Add the peanut butter, chocolate chips, and butter to a small microwave-safe bowl.
Microwave in 30-second increments, mixing in between, until the chocolate is melted. It should take just about 1 minute total. Stir until smooth.
Pour the chocolate over the cocoa puff cereal. Stir until the cereal is completely coated.
Whisk together the cocoa powder and powdered sugar.
Pour the powdered sugar mixture over the cereal and stir until the cereal is covered. Alternatively, you can place everything in a large Ziploc bag and shake it until the powdered sugar covers the cereal.
Dump the reindeer poop out onto a baking sheet and allow to cool briefly. Serve in a bowl or portion out into cellophane bags as a gift!