In a Dutch oven, over medium heat, cook sausage, onion and garlic in oil until onions are tender. Add green pepper, mushrooms, salt and seasoning; continue to cook for 4 minutes. Stir in tomatoes, water and basil. Simmer, uncovered, for 20-25 minutes. Add prepared spaghetti to sauce; toss to coat evenly. Spoon one-half of the pasta mixture into a greased 2-½ quart baking dish. Sprinkle with one-half of the cheese. Top with remaining pasta mixture and cheese. Bake, covered, at 375F for 20-25 minutes. Remove cover, bake 5 minutes longer. Serve.