Heat oil; cook onion for 4-5 minutes, garlic for 1 minute. Add beef and cook for 6-8 minutes. Add marinara, tomatoes, oregano, salt, and pepper; simmer for 10 minutes.
Mix ziti, sauce, ricotta, 1 cup mozzarella, Parmesan, and basil.
Spread in a greased 9x13-inch dish; top with 1 cup mozzarella.
Bake at 375°F, covered, for 20 minutes; uncover and bake for 10-15 minutes.