Peanut Butter Balls

1 cup sifted powdered sugar
1/2 cup creamy peanut butter
3 tablespoons butter or margarine, softened
1 bag chocolate chips
1-2 teaspoons shortening (just enough to thin chocolate chips for dipping)
Finely chopped peanuts for garnish, if desired

Stir together powdered sugar, peanut butter and butter until well mixed. Shape peanut butter mixture into 1 inch balls, placing them on a baking sheet covered with waxed or parchment paper. Let balls stand for 20 minutes until dry. Melt the chocolate chips and shortening in a double boiler. Drop balls one at a time in melted chocolate. Using a fork, remove from the chocolate, letting excess chocolate drip off. Place back on the waxed paper. Let dry about 1 minute, then sprinkle with chopped nuts if desired. Let stand until dry. Store tightly covered in a cool dry place.