Flour Frosting

This is Bryan's most favorite frosting. Tradtion is for him to enjoy this on his red velvet cake.
 
  1 c. milk
  5 tbsp. flour
  1 c. butter
  1 c. powdered sugar, sifted
  1 tsp. vanilla

Combine milk and flour in saucepan and bring to boil over medium heat stirring constantly.
Cook until smooth and thick.
Place in refrigerator until cooled.
Cream and beat together butter, sugar and vanilla until fluffy.
Add flour mixture and beat at high speed until very soft, light
and fluffy. (This may take 10 minutes on high speed to break up and distribute flou mixture throughout.)

Must be kept refrigerated.