Preheat the oven to 375°F and spray a 9 x 13 x 2½-inch baking dish with nonstick spray; set aside.
Heat 1 tablespoon olive oil in a large skillet over medium-high heat.
Add the diced zucchini, chopped mushrooms, diced carrots, and diced onion; cook 4–5 minutes until vegetables are tender.
Add the spinach and cook about 1 minute until wilted.
Stir in the crushed tomatoes, tomato sauce, tomato paste, Italian seasoning, granulated sugar, and chopped fresh basil; simmer over low heat about 10 minutes, then season with salt and pepper to taste.
Meanwhile, bring a large pot of salted water to a rolling boil. Cook the lasagna noodles 8 minutes or until al dente, then drain and rinse with cold water to stop cooking.
In a medium bowl, combine the ricotta, grated Parmesan, and egg until smooth.
Assemble the lasagna: spread 1 cup of the vegetable-tomato mixture in the bottom of the prepared dish. Lay a single layer of noodles over the sauce, spread 1/2 cup of the ricotta mixture, and sprinkle a handful of mozzarella. Repeat layers until ingredients are used, finishing with the remaining mozzarella on top.
Cover the dish with foil and bake 20 minutes. Remove foil and bake an additional 20–25 minutes until heated through and the top is bubbly and browned.
Let the lasagna rest 10 minutes before slicing and serving.
