3 tbsp. butter
3 tbsp. flour
1 c. milk
1/4 tsp. salt
1/8 tsp. pepper
1/2 lb. grated American cheese
1 (10 oz.) pkg. frozen chopped spinach or broccoli, thawed and drained well
1/2 c. finely chopped onion
3 eggs, separated

Melt butter in saucepan; stir in flour to make smooth paste. Add milk and seasonings; cook 5 minutes. Add cheese and stir until melted. Fold in spinach and onion. Fold in well beaten egg yolks. Lightly fold in egg whites, beaten until stiff but not dry. Pour into 1 1/2 - 2 quart flat baking dish. Set in pan of hot water (1/2 inch) and bake in preheated moderate oven (350 degrees) for 1 hour.