1 1/2 – 2 cups powdered sugar, plus more as desired
Method
Add your cereal to a large mixing bowl and line a large baking sheet with parchment paper or wax paper.
Make the melted chocolate mixture: Add the chocolate chips, peanut butter, and salted butter to a large microwave safe bowl. Microwave for 30 seconds at a time until melted, stirring between each interval. Once the mixture is melted, stir in the vanilla extract, salt, and espresso powder (if using).
Pour the melted chocolate mixture over the cereal and then use a silicone spatula to gently toss the cereal in the chocolate mixture until well coated, being sure not to crush the cereal.
Next, pour half of the powdered sugar into a gallon sized food-safe storage bag and then add half the cereal mixture. Shake the bag to gently toss until all of the cereal is well coated with powdered sugar (add more powdered sugar if needed) and then transfer to the lined sheet pan and spread in an even layer. Repeat until all of the cereal has been coated.
Let the puppy chow sit until it is completely cooled and set. Store in an airtight container in a cool, dry area or in the fridge or freezer!