Preheat your oven to 375°F (190°C).
Cook the lasagna noodles according to the package instructions, then drain and set aside.
In a skillet, sauté the zucchini, bell pepper, and mushrooms until tender.
Add spinach and cook until wilted. Season with salt, pepper, and Italian seasoning.
In a bowl, mix ricotta cheese with a pinch of salt and pepper.
Spread a layer of marinara sauce on the bottom of a baking dish.
Layer three lasagna noodles over the sauce.
Add half of the ricotta mixture, followed by half of the sautéed vegetables.
Sprinkle a layer of mozzarella cheese over the vegetables.
Repeat the layers, finishing with noodles, marinara sauce, and mozzarella cheese on top.
Cover with foil and bake for 30 minutes, then remove foil and bake for an additional 15 minutes until golden brown.