Preheat your oven to 375°F (190°C) to ensure a perfectly baked ziti.

Bring a large pot of salted water to a boil. Cook the ziti pasta until al dente, about 8-10 minutes, then drain.

In a skillet over medium heat, add olive oil and sauté the bell peppers and mushrooms for 5-7 minutes until softened. Stir in zucchini and spinach, cooking until spinach wilts, about 2 minutes.

In a large mixing bowl, combine the cooked pasta, sautéed vegetables, and marinara sauce. Mix until evenly coated.

Spread half of the pasta mixture in a greased baking dish, layer with half of the mozzarella cheese, then add the remaining pasta mixture. Finish with remaining cheese and a sprinkle of parmesan.

Bake for 25-30 minutes or until melted and bubbly.

Remove from the oven, let cool for a few minutes, and serve warm.