2 (10 oz.) pkgs. frozen spinach, thawed
1/4 c. butter
1/4 c. flour
3/4 c. milk
2 tsp. grated onion
1 tsp. salt
3 oz. cheddar cheese
3 oz. American cheese
1 1/2 tbsp. Parmesan cheese
6 eggs, separated
1 1/2 tbsp. lemon juice

Thoroughly drain thawed spinach. Heat butter. Add flour gradually. Slowly stir in milk and cook, stirring constantly until thickened. Stir in all cheeses and grated onion until cheese is melted.

Beat egg white until consistency of meringue and set aside. Beat yolks; gradually stir in hot mixture. Mix until smooth. Add drained spinach and mix until blended. Fold in beaten egg whites. Pour into greased 9 x 13 inch pan.

Set 9 x 13 inch pan into larger pan with small amount of water. Bake at 350 degrees for approximately 1 hour or until knife inserted into center of pan comes out clean.