Prepare 1 box chocolate cake mix according to directions and bake in 9x13 inch baking dish. Set aside to cool.
Mix 5 tablespoons of flour with 1 1/4 cup milk. Cook over low heat until thickened. Cool.
Cream: 1 cup of sugar, 1 cup of Crisco, 1 stick of margarine. Add cooled milk mixture. Spread on cake. To frost, melt 3 ounces of Baker's chocolate with 1 stick of margarine and 2 1/2 tablespoons of water. Cool. Then add 1 egg, 1 teaspoon of vanilla and 2 cups of powdered sugar. Frost cake and refrigerate.