Preheat the oven to 350 degrees F.
Melt the butter in a large skillet. Saute the onions and mushrooms in the butter. Boil green beans in chicken broth for 10 minutes and drain. Add the green beans, mushroom soup, onion rings, and House Seasoning, to taste, to the onion mixture. Stir well. Pour into a greased 1 1/2-quart baking dish. Bake for 20 minutes, then top the casserole with the Cheddar and bake for 10 minutes longer, or until the casserole is hot and cheese is melted.
Edited by wildweaselmi