01 - Line a 9x13-inch baking pan with parchment paper or lightly grease with cooking spray.
02 - Place Rice Krispies cereal in a large mixing bowl.
03 - Combine chocolate chips, peanut butter, and butter in a microwave-safe bowl. Microwave in 30-second intervals, stirring between each, until melted and smooth, approximately 1-2 minutes total.
04 - Stir vanilla extract into the melted chocolate mixture until fully incorporated.
05 - Pour the chocolate-peanut butter mixture over the Rice Krispies. Gently fold until all cereal pieces are evenly coated.
06 - Transfer mixture to the prepared pan. Press lightly into an even layer, taking care not to crush the cereal.
07 - Place powdered sugar in a large zip-top bag. Cut the Rice Krispies mixture into squares, then gently toss pieces in the powdered sugar until well coated.
08 - Place coated squares on a wire rack or parchment-lined tray. Allow to set for 10 minutes before serving.