01 - Boil ziti pasta in a large pot of salted water until al dente, then drain thoroughly.
02 - In a large mixing bowl, toss cooked ziti with tomato sauce and chopped spinach until evenly coated.
03 - Transfer half of the pasta mixture into a greased 9x13-inch baking dish, sprinkle with half the mozzarella and half the Parmesan, then add the remaining pasta and top with remaining cheeses.
04 - Bake uncovered in a preheated oven at 375°F (190°C) for 25–30 minutes until cheese is bubbly and lightly golden.
05 - Allow to cool for 5 minutes before serving family-style.