Preheat your oven to 375°F (190°C).

Cook the ziti pasta in a large pot of salted water according to the package instructions until al dente. Drain and set aside.

In a large skillet, heat the olive oil over medium heat. Add the chopped onion and minced garlic. Sauté until softened, about 3-4 minutes.

Stir in the chopped zucchini and cook for another 5 minutes. Add the spinach and let it wilt.

Next, add the crushed tomatoes, tomato sauce, Italian seasoning, salt, and black pepper. Mix well and simmer for 10 minutes.

In a large bowl, combine the cooked ziti with the tomato mixture and ricotta cheese. Make sure everything is well mixed.

Transfer half of the ziti mixture into a baking dish. Sprinkle half of the mozzarella and half of the Parmesan cheese on top. Add the remaining ziti mixture and finish with the remaining mozzarella and Parmesan cheese.

Cover the dish with aluminum foil and bake for 25 minutes. Then, remove the foil and bake for another 15-20 minutes, or until the cheese is bubbly and golden.

Let it cool for a few minutes before serving.