I never buy those canned French Fried onions that go into the green bean casserole because it's extra expense. If I were to decide to splurge and buy some I would try this recipe:

Corn and Onion Casserole
1 (3 1/2 oz) can French Fried Onions
1/2 cup green pepper, chopped fine
2 tablespoons butter
1 (1 lb) can cream style corn
3 tablespoons pimiento, chopped
2 eggs, slightly beaten

Saute the green pepper in the butter until tender. Add corn, pimiento, eggs, and 1/2 of the onions, crushed. Pour into a greased 1 1/2 quart casserole dish. Bake at 350 degrees fro 25 to 35 minutes or until firm. Sprinkle with the remaining onions and bake 10 to 15 minutes longer.

Years ago I made the traditional green bean casserole with those onions in the crockpot because I didn't have oven room. It came out good.

Green Bean and Onion Casserole

1 can cream of mushroom soup
1 can French cut green beans
3/4 teaspoon yellow mustard
1 (3 1/2 oz) can French Fried Onions

Combine the mushroom soup, green beans and mustard in a crockpot. Crush up half of the onions and stir in. Heat up, allowing enough time for it to simmer about 30 to 45 minutes. Some time before serving sprinkle the rest of the onions on top.