In a large bowl, mix the butter and peanut butter together until smooth. Add in the powdered sugar until a thick dough forms. Fold in the Reese's pieces.
Roll the mixture into balls, and place onto a plate. Freeze for at least 20 minutes. Place the 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 ball into the melted chocolate. Set onto a plate, and let sit until it is completely set.
