Cook chicken in water. Debone chicken. Cook spaghetti in broth of cooked chicken. In a skillet, saute bell pepper and onion in butter. Add cheese,soup and tomatoes. Drain spaghetti noodles. Mix chicken with your noodles then add tomatoe mixture. Mix well. Pour into a 3 quart casserole dish and bake 25-20 minutes at 375 degrees. Serve with a green salad and bread!