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

In a small saucepan, heat milk and flour over low heat. Stir until it forms a thin paste. Remove from heat and let cool. Cream together sugar, butter, Crisco shortening and vanilla. Add paste after it cools. Beat until smooth. Frost cooled cake.