Preheat your oven to 375°F (190°C).
Cook lasagna noodles according to package instructions; drain and set aside.
In a skillet, sauté zucchini, bell pepper, and mushrooms until tender.
Add spinach and cook until wilted; season with Italian seasoning.
In a bowl, mix ricotta cheese with half of the Parmesan cheese.
Spread a layer of marinara sauce on the bottom of a baking dish.
Layer 3 noodles over the sauce, followed by half of the ricotta mixture.
Add half of the sautéed vegetables and a sprinkle of mozzarella cheese.
Repeat the layers, finishing with noodles and remaining sauce on top.
Sprinkle with remaining mozzarella and Parmesan cheese, then cover with foil.
Bake for 25 minutes, then remove foil and bake for an additional 15 minutes until golden.