Cheesy Green Bean Casserole

5 Cans cut green beans, drain 4 cans
4 t. Margarine
4 t. Flour
1/2 t. Salt
1/4 t. Ground pepper
2 t. sugar
2 C Fat-free sour cream
2 T dried onions
1 C Non-fat cheddar cheese
1 C Grated non-fat mozzarella cheese
1 C Cornflakes, crushed

Combine margarine, flour, salt, pepper, sugar and liquid from one can of green beans and heat in medium saucepan.   Stir in sour cream and onion flakes.  Stir green beans into sauce.  In a 9x13 inch baking dish sprayed with a non-fat cooking spray, layer green bean mixture with cheese, top with crushed cornflakes.  Bake at 350 degrees for 20-30 minutes.