In a medium mixing bowl, mix peanut butter, butter, vanilla, and confectioners' sugar (until mixture becomes stiff).
Shape into balls and place on a pan covered with wax paper. Place in refrigerator.
In double boiler, melt chocolate and shortening. (Chef's note: you can make your own double boiler by placing a glass bowl over a small pot of boiling water).
Pour into bowl and dip balls with chocolate.
Refrigerate for thirty minutes on wax paper until chocolate becomes firm.