Line an 8x8-inch baking dish with parchment paper, leaving overhangs for easy removal. Set aside.
In a microwave-safe bowl, combine the chocolate chips, peanut butter, and butter. Heat in 30-second intervals, stirring between each, until smooth and fully melted.
1 & 3/4 cup semi-sweet or milk chocolate chips, 2/3 cup creamy peanut butter, 3 tablespoons unsalted butter
Place the Chex cereal in a large mixing bowl. Pour the melted chocolate mixture over the cereal and gently fold to coat evenly, being careful not to crush the cereal.
4 cups Chex cereal
Transfer the mixture into the prepared baking dish. Use a spatula to press the mixture down firmly into an even layer.
Place the pan in the refrigerator for 1-2 hours or until the bars are firm and set.
Remove from the pan using the parchment overhang. Slice into bars slowly with a serrated knife, toss in the powdered sugar to coat and enjoy!
1 ½ cups powdered sugar