Step 1

Place the cereal in a large bowl; set aside. Place the cocoa powder, 1/4 cup of the powdered sugar, and 1/4 teaspoon of the salt in a bowl; whisk to combine; and then transfer to a gallon-sized zip-top bag.

Step 2

Place the Andes mint chips and butter in a microwave-safe bowl and microwave in 30-second bursts, stirring between bursts, until melted. (If you don't have a microwave, melt the mixture in a double boiler instead.) Immediately pour over the cereal and stir gently until evenly coated. Transfer the cereal to the zip-top bag and shake until well-coated with the cocoa powder mixture. Add 1 tablespoon of the powdered sugar and shake again.

Step 3

Spread the puppy chow onto a rimmed baking sheet and sprinkle with remaining 1/4 teaspoon salt. Let cool completely.