Spinach Souffle

Make a cream sauce of:
3 tbs. butter
3 tbs. flour
1 c. milk
1 tsp. salt
Add:
3/4 c. grated cheese, packed
1 -10 oz box frozen spinach, cooked and
water squeezed out.
Small piece of onion, chopped
3 beaten egg yolks
Mix all:
Fold in 3 stiffly beaten egg whites.
Put in 1 1/2 qt. casserole or souffle pan.
Stand in pan of water & bake 1 hr.