Heat oven to 350. Bring a large pot of salted water to a boil and add ziti, cook until tender, about 8 minutes. Drain pasta. Place the ziti in a large bowl mix with ricotta and half of the mozzarella. Grease a 9x13 pan. Spread half of the spaghetti sauce on bottom of the pan, add the ziti mixture and cover with the remaining sauce, sprinkle with parmesan and the remaining mozzarella. Bake uncovered for 20 to 30 minutes, until the casserole bubbles on the edges.