Fry bacon until crisp. Saute onions and mushrooms in bacon drippings until tender.
Crumble 4 slices of bacon and combine with onions, mushrooms, beans and mushroom soup in casserole.
Bake at 350°F for 30 min or until soup bubbles. Sprinkle French onions on top and broil until brown. Then lightly sprinkle shredded cheese on top and let stand until melted. Crumble remaining bacon slices for garnishment and serve.