Blend 1/4 cup flour into 1/2 cup butter or margarine, heated, in a heavy saucepan.
Cook and stir until bubbly.
Mix in 2 cups chicken broth and bring rapidly to boiling, stirring constantly; cook 1 to 2 minutes.
Vigorously stir about 3 tablespoons of the hot sauce into 4 fork-beaten egg yolks.
Immediately blend into mixture in saucepan.
Cook over low heat 3 to 5 minutes, stirring constantly.
Blend in 1/2 cup butter or margarine.