1-1/2 sticks butter or margarine
1 cup peanut butter
1 teaspoon vanilla
1 pound box confectioners sugar

In a saucepan, combine butter, peanut butter and vanilla over low heat until melted (do not boil) stirring constantly.  Remove from heat and stir in confectioners sugar.  Stir quickly and put in greased 8 x 8 glass baking dish.  Refrigerate.