Heat in saucepan-
1 cup butter or margarine (2 cubes)
1 cup water. Pour over dry ingredients.
Stir in milk, eggs, vanilla.
Pour thin batter unto a greased and floured cookie sheet with sides. Or a jelly roll pan. Bake 20 mins at 400 degrees.
While cake is baking, prepare frosting.
Heat to boiling the butter, cocoa and the milk. Pour over 4 cups powdered sugar. Spread frosting over hot cake.