Baked Spaghetti with Mushrooms and Olives

2 tablespoons olive oil Ask a question about this ingredient

1 onion, chopped Ask a question about this ingredient

1 pound ground beef Ask a question about this ingredient

2 Portobello mushroom caps, rinsed and chopped Ask a question about this ingredient

1 26 oz. jar mushroom and olive pasta sauce Ask a question about this ingredient

1 2.25 oz can black olive bits Ask a question about this ingredient

1 small zucchini chopped 3/4 ", optional Ask a question about this ingredient

2 fresh tomatoes, medium, squeezed and chopped, optional Ask a question about this ingredient

1 small can sliced mushrooms, drained, optional Ask a question about this ingredient

1 cup Parmesan cheese, grated Ask a question about this ingredient

1 packet Pizza Cheese, shredded Ask a question about this ingredient

1 pound spaghetti Ask a question about this ingredient