Mystery Icing
["4 Tbsp. all-purpose flour", "1 c. milk", "1 c. sugar", "1/2 c. butter", "1/2 c. vegetable shortening", "dash of salt", "1/4 tsp. vanilla extract"]
["Blend the flour and milk.", "Cook until mixture thickens to consistency of cream.", "Cool, but don't chill.", "Cream sugar, butter and shortening, adding salt and vanilla.", "Add the slightly cooked flour mixture and continue beating until very fluffy.", "Yield: Icing for a 2-layer cake."]
["flour", "milk", "sugar", "butter", "vegetable shortening", "salt", "vanilla extract"]