Amanda's Portobello Mushroom Green Bean Casserole

2/3 stick butter
4 strips bacon cooked and crumbled
1 cup diced onion
1 cup sliced mushrooms
4 cups cut green beans
2 containers fried onion rings
2 -10 3/4 oz cream of mushroom soup. (Amanda has a Portobello mushroom concentrate that came from Trader Joes I think.)
2 cup cheddar
Salt
Pepper
Garlic powder

Method:
Wednesday
Boil and shock green beans
Sauté mushrooms and onions in butter.
Add green beans, mushroom soup, 3/4 of the onion rings, bacon, 1/3 of the cheese, and seasonings and mix well.
Pour into a well greased 3 quart casserole, cover, and chill until 40 mins prior to serving.

T-day dinner minus 40 minutes
Bake 20 mins at 350, remove and top with cheddar cheese and additional onion rings and bake another 10 mins until casserole is hot and cheese is melted.