Mix together peanut butter, butter, and powdered sugar. Form into small balls, and place on a tray lined with parchment or wax paper
Freeze balls for about 10 minutes
Place chocolate and shortening in a dish, and microwave in 30-sec intervals, stirring between each, until completely melted and smooth.
Dip frozen balls into chocolate, and put them back on the lined tray. Chill about 30 minutes to set. Store in refrigerator