Fry bacon until crisp; crumble and set aside. Sauté onion in bacon drippings until tender. Drain off excess drippings. Add stewed tomatoes and heat. Drain cans of green beans and place in 2 quart* casserole dish. Add tomato mixture and crumbled bacon and mix. Top with shredded cheese. Bake for 30 minutes at 350°. *Use larger size casserole dish when using 4 cans of green beans.