01 - Line a 9x13-inch baking pan with parchment paper or lightly grease with cooking spray to prevent sticking.
02 - Place the Rice Krispies cereal in a large mixing bowl, ensuring plenty of space for mixing.
03 - Combine chocolate chips, peanut butter, and butter in a microwave-safe bowl. Microwave in 30-second intervals, stirring thoroughly between each, until completely melted and smooth, approximately 1-2 minutes total.
04 - Stir the vanilla extract into the melted chocolate-peanut butter mixture until fully incorporated.
05 - Pour the warm chocolate mixture over the Rice Krispies. Gently fold with a spatula until all cereal pieces are evenly coated without crushing them.
06 - Transfer the coated cereal mixture to the prepared pan. Press lightly with the spatula to form an even layer, being careful not to compact the cereal too tightly.
07 - Place powdered sugar in a large zip-top bag. Cut the Rice Krispies mixture into squares, then add a few pieces at a time to the bag. Gently shake until each piece is thoroughly coated in powdered sugar.
08 - Arrange the coated squares on a wire rack or parchment-lined tray. Allow to set for 10 minutes before serving.