01 -
Heat the oven to 300 F. Spread the dry brownie mix on a parchment-lined baking sheet and bake for 5 minutes, stirring once, until the mix reaches 165 F. Cool completely.
02 -
Whisk the cooled brownie mix, powdered sugar, cocoa powder, and salt in a medium bowl until evenly combined.
03 -
Place the cereal in a very large mixing bowl. Set out a large zip-top bag or a lidded container for shaking.
04 -
Combine the chocolate chips, peanut butter, and butter in a microwave-safe bowl. Microwave in 20-second bursts, stirring each time, until smooth. Stir in the vanilla.
05 -
Pour the warm chocolate mixture over the cereal. Fold gently with a spatula until the cereal is evenly coated but not crushed.
06 -
Transfer the coated cereal to the bag or container. Add the brownie powder mixture, seal well, and shake until the cereal is coated.
07 -
Spread the puppy chow on a parchment-lined baking sheet until set. Toss with mini chocolate chips if using, then store airtight.