Preheat oven to 400°F (200°C).
Toss zucchini, bell peppers, eggplant, mushrooms, and onion with olive oil, salt, and pepper. Spread on a baking sheet and roast for 20-25 minutes.
Reduce oven temperature to 375°F (190°C).
In a baking dish, spread a thin layer of marinara sauce. Layer with lasagna noodles, roasted vegetables, ricotta cheese, mozzarella cheese, and Parmesan cheese. Repeat layers, ending with cheese on top.
Cover with foil and bake for 30 minutes. Remove foil and bake for an additional 10-15 minutes until cheese is bubbly and golden.
Let lasagna cool for 10 minutes before serving.