Not Your Ordinary Green Bean Casserole

From my sweet friend, Debi. This is even better than traditional green bean casserole!

2 cans French cut green beans, drained (or thawed frozen)
3 T. butter
2 heaping T. flour
1 t. salt
2 t. sugar
4 t. grated onion
1 c. sour cream
8 oz. grated Swiss cheese
2 c. crushed corn flakes
1/4 c. melted butter

Cook beans according to package directions. Place in a 9x13 dish. Melt butter in a saucepan and blend in flour. Add salt, sugar, onion, sour cream, and cheese. Pour over beans. (You can add milk to thin it, if desired.) Top with buttered corn flakes. Bake at 350 degrees for 20-30 minutes.