2 tbsp. cornstarch
1 c. milk
1/2 c. butter
1 c. sugar
1/3 c. shortening
1 tsp. vanilla

Combine cornstarch and milk in saucepan. Cook and stir until thick. Cool mixture. (Recipe will not work if it is warm.) Combine butter and sugar, shortening and vanilla; mix and then add milk mixture to sugar mixture. Mix at high speed until fluffy.