Buttercream Frosting - cooking recipe

Ingredients

5 Tbsp. flour
1 c. milk
1/2 c. butter or margarine
1/2 c. white shortening
1 c. granulated sugar
1 tsp. vanilla

Preparation

Blend flour and milk until smooth.
Cook over low heat until thickened and boiling (this is the tricky part, take your time or it will scorch).
Cool to room temperature.
Cream butter (or margarine) and shortening.
Gradually add sugar and beat until completely dissolved.
Add vanilla.
Add the cooled flour and milk mixture a tablespoon at a time.
Beat at high speed until light and fluffy.