1 c. milk
1/4 c. flour
1 tsp. vanilla
1 c. sugar
1/2 c. butter or margarine
1/2 c. shortening

In a small saucepan, cook flour and milk until thick, stir well. Set aside to cool, (keep mixture covered as it cools). In a bowl beat sugar, margarine (or butter) and shrotening using high speed of mixer, until fluffy. Add the milk mixture and vanilla. Continue beating until the icing is very fluffy.