Mix sugar, cocoa and salt in 2-quart saucepan. Add water. Heat to boiling stirring constantly. Boil and stir 2 minutes. Stir in milk; heat just until hot (do not boil). Stir in 1/4 ts vanilla if desired.

Beat with hand beater until foamy or stir until smooth. Serve immediately. 9 servings (about 2/3 cup each);115 calories per serving.