Combine the chocolate chips, peanut butter, and butter in a bowl. Microwave for 30 seconds, stir, and repeat until smooth.
In a large bowl, combine the Chex and the chocolate mixture and toss well to coat.
Transfer to a ziplock bag, add the icing sugar, and toss well until the cereal is fully coated.
Spread on a baking sheet and let sit for 15 minutes.
Toss with extra chocolate, pretzels, Reese's Pieces, and Halloween candy.
Store in a large container with a lid (refrigerate to keep it crisp).