3 tbsp. flour
1 c. milk
1/2 c. butter, room temp.
1/2 c. vegetable shortening, room temp.
1/8 tsp. salt
1 c. granulated sugar
1 tsp. vanilla or other flavoring

Mix flour and milk until smooth. Cook slowly, stirring constantly until mixture thickens. Remove from heat and cool. Add butter and shortening and blend at low speed. Add salt. Beat at high speed until smooth and fluffy. Blend in sugar, beat at high speed until sugar crystals dissolve. Add vanilla, beat 1 minute at high speed.