01 - Line a 9x13-inch baking pan with parchment paper or lightly grease with butter or cooking spray.
02 - Place the Rice Krispies cereal in a large mixing bowl and set aside.
03 - In a microwave-safe bowl, combine chocolate chips, peanut butter, and butter. Microwave in 30-second intervals, stirring between each, until melted and smooth, about 1 to 2 minutes total.
04 - Stir in the vanilla extract until fully incorporated into the chocolate mixture.
05 - Pour the chocolate-peanut butter mixture over the Rice Krispies. Gently fold with a spatula until all cereal is evenly coated without crushing the flakes.
06 - Transfer the mixture to the prepared pan. Press lightly into an even layer without compacting the cereal too tightly.
07 - Cut the mixture into 16 equal-sized squares while still slightly warm.
08 - Place powdered sugar in a large zip-top bag. Add the Rice Krispies squares a few at a time and gently shake until evenly coated.
09 - Place coated squares on a wire rack or parchment-lined tray to set for 10 minutes before serving.