Preheat your oven to 375°F (190°C). Lightly grease a 9x13 inch baking dish.
Cook lasagna noodles according to package directions until al dente. Drain and set aside.
While the noodles cook, toss sliced zucchini, squash, and eggplant with olive oil, salt, and pepper. Roast on a baking sheet for 15-20 minutes until tender.
In a bowl, combine ricotta, one egg, 1/2 cup mozzarella, 1/4 cup Parmesan, basil, and oregano. Mix well.
Start layering: spread 1 cup marinara sauce on the bottom of the baking dish. Layer 4 lasagna noodles, slightly overlapping.
Spread 1/3 of the ricotta mixture over the noodles, then layer 1/3 of the roasted vegetables. Add a layer of fresh spinach and bell peppers.
Repeat layers twice more, ending with vegetables and sauce on top.
Sprinkle remaining mozzarella and Parmesan cheese over the top.
Cover with foil and bake for 25 minutes. Remove foil and bake for an additional 25 minutes until bubbly and golden brown.
Let rest for 15 minutes before serving.