In a large bowl, mix together butter, peanut butter, and powdered sugar until combined. Fold in the Reese's pieces. Roll the mixture into balls and set onto a plate.
Place the white chocolate chips into a microwave-safe bowl, and heat in the microwave in 30-second intervals, stirring well until it is fully melted and smooth. Fully coat each peanut butter in the chocolate and set onto a plate. Let sit until it is completely set.