Hershey'S Disappearing Cake
["1/4 c. butter or margarine", "1/4 c. shortening", "2 c. sugar", "1 tsp. vanilla", "2 eggs", "3/4 c. Hershey's cocoa", "1 3/4 c. unsifted all-purpose flour*", "3/4 tsp. baking powder", "3/4 tsp. baking soda", "1/8 tsp. salt", "1 3/4 c. milk"]
["*May substitute self-rising flour and omit baking powder, baking soda and salt."]
["butter", "shortening", "sugar", "vanilla", "eggs", "cocoa", "flour", "baking powder", "baking soda", "salt", "milk"]