combine peanut butter, butter, and chocolate chips in a saucepan. stirring constantly over med-low heat. After its melty, add vanilla. place crispix in a large bowl. pour over chocolate mixture. mix together until its well coated. place 1 cup of powdered sugar in a gallon size ziplock, with 1/3 of the cereal mixture. shake to coat. pour into resealable container. repeat twice.