01 - Line a 9x13-inch baking pan with parchment paper or lightly grease it to prevent sticking.
02 - Place the Rice Krispies cereal in a large mixing bowl, ensuring you have enough space to coat evenly.
03 - In a microwave-safe bowl, combine chocolate chips, peanut butter, and butter. Microwave in 30-second intervals, stirring 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 well 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 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 mixture into squares and add a few pieces at a time to the bag. Shake gently until evenly coated in sugar.
08 - Arrange the coated squares on a wire rack or parchment-lined tray. Let set for 10 minutes to allow the chocolate to firm slightly before serving.