Spinach Souffle - cooking recipe

Ingredients

1 c. cooked spinach
1/4 c. butter
1/4 c. flour
1 c. milk
1/2 tsp. salt
1/4 tsp. dry mustard
1/4 tsp. pepper
1 c. shredded American cheese
3 eggs, separated
1/4 tsp. cream of tartar
lemon juice (may be added; optional)

Preparation

Melt the butter in saucepan.
Blend in flour.
Add milk and cook until mixture is thick.
Blend in seasonings and cheese and cook until the cheese melts.
Stir a little of the hot mixture into the 3 egg yolks which have been beaten.
Fold in the cooked spinach.