1/2 c. butter
2 1/2 tbsp. flour
1/4 tsp. salt
1/2 c. milk
3 c. sifted confectioners' sugar
1/2 tsp. vanilla

Melt butter in saucepan; remove from heat and blend in the flour and salt. Slowly stir in milk. Bring to a boil, stirring constantly. Boil 1 minute. Remove from heat and stir in sugar and vanilla. Beat until right consistency to spread.