1-2 sticks butter (do not use whipped butter)
1 c. peanut butter
1 box confectioners' sugar
1 tsp. vanilla

Melt butter and peanut butter in a heavy saucepan. Turn heat as low as possible, add box of confectioners' sugar all at once. Add vanilla. Stir until all sugar lumps are dissolved. Pour into a 9 x 9 inch pan until cold.