Prepare the cereal: Place 9 cups of Chex™ cereal in a large mixing bowl and set aside.
Melt the chocolate mixture: In a microwave-safe bowl, combine chocolate chips, peanut butter, and butter. Microwave for 30 seconds, stir, then continue heating in 20-second intervals until smooth and fully melted.
Add vanilla: Stir in vanilla extract once the mixture is melted and glossy.
Coat the cereal: Pour the chocolate-peanut butter mixture over the cereal. Gently stir until all pieces are evenly coated.
Add powdered sugar: Transfer the coated cereal into a large resealable bag, add powdered sugar, seal, and shake until every piece is fully covered.
Cool and serve: Spread the mixture on a parchment-lined baking sheet to cool for 10–15 minutes. Once dry, store in an airtight container.
Enjoy: Serve as a party snack, dessert, or sweet movie-night treat!