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

Cook milk and flour until thick. Set aside to cool. Blend together butter, shortening and sugar for 4 minutes. Continue mixing until well blended. Add cooled milk/flour mixture to the butter/shortening/sugar mixture, blending well. Add 2 teaspoons vanilla. Beat all ingredients together for 4 more minutes.