3 tbsp. flour
3/4 c. milk
1/4 c. butter
1/4 c. shortening
1/2 c. sugar
1 tsp. vanilla

Cook flour and milk over low heat until thick. Set aside until cold. Cream butter and shortening at high speed for 4 minutes. Add sugar gradually. Beat for 4 minutes longer. Add flour paste; beat 4 minutes longer. Add vanilla; blend.