Bake cake according to package directions in a cookie sheet with sides.
Jelly roll pan can be used.
Bake 20 25 minutes.
While cake cools, mix 1 1/4 cups milk (carnation), with 5 tablespoons flour. Heat and stir until thick. Cool completely before adding next ingredients.
Cream well; 1 cup sugar, 1 teaspoon vanille, 1/2 cup all vegetable shortening, 1 stick margarine. Add to cooled mixture. Beat until fluffy. Spread on cooled cake, refrigerate for 4 5 hours.
Ice with 1 can dark whipped frosting. Store in refrigerator.
Not a NESTLÉ®-tested recipe.