Heat oil in Dutch oven. Cook and stir beef and onion in hot oil until beef is light brown; drain off fat. Stir in remaining ingredients except zucchini and cheese. Heat to boiling; reduce heat. Cover and simmer, stirring occasionally, 1 hour. Heat oven to 350. Trim ends from zucchini; cut zucchini lengthwise in half. Place cut sides up in greased baking dish, 15x9x2 inches. Pour on tomato sauce. Bake uncovered 45 minutes. Serve with cheese.