Never Fail Fudge - cooking recipe

Ingredients

1 (1 lb.) box powdered sugar
1/4 c. cocoa
1/4 c. milk
1/4 tsp. vanilla
6 Tbsp. ???

Preparation

Combine all ingredients in the top of a double boiler.
Stir until smooth and blended.
Pour fudge into buttered 13 x 9-inch pan.
Chill until firm.