1/4 c. flour
1 c. milk

Cook over medium heat, stirring constantly, until thick. Cool, and place in a large mixing bowl with;

1 c. softened butter
1 c. sugar
1 tsp. vanilla

Beat with electric mixer until sugar is dissolved, about 4-5 minutes. You can add almond or lemon flavoring, or melted chocolate, at this point. This will be a soft, not-too-sweet frosting, enough for a 9x13 inch cake, or to cover an angel food cake.