01 - Line a 9x13-inch baking pan with parchment paper or lightly grease with cooking spray to prevent sticking.
02 - Place 6 cups of Rice Krispies cereal in a large mixing bowl and set aside.
03 - Combine chocolate chips, peanut butter, and butter in a microwave-safe bowl. Microwave in 30-second intervals, stirring between each, until completely melted and smooth, approximately 1-2 minutes total.
04 - Stir in vanilla extract until fully incorporated into the chocolate mixture.
05 - Pour the warm chocolate-peanut butter 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 baking pan. Press lightly into 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 16 squares and gently toss pieces in the bag until thoroughly coated with powdered sugar.
08 - Transfer coated squares to a wire rack or parchment-lined tray. Let set for 10 minutes before serving to allow the coating to firm up.