Preheat oven to 375°F (190°C).
Cook lasagna noodles according to package instructions. Drain and set aside.
In a large saucepan, heat olive oil over medium heat. Add garlic and sauté until fragrant.
Add chopped vegetables (spinach, mushrooms, zucchini, bell peppers) and cook until tender. Season with salt and pepper.
In a baking dish, spread a layer of marinara sauce. Place a layer of lasagna noodles on top.
Spread a layer of ricotta cheese, followed by a layer of cooked vegetables, and a layer of mozzarella cheese. Repeat layers until ingredients are used up, ending with a layer of marinara sauce and a sprinkle of Parmesan cheese on top.
Cover with aluminum foil and bake for 30 minutes. Remove foil and bake for an additional 15 minutes, or until cheese is bubbly and golden.
Let lasagna cool for 10 minutes before serving.