Preheat the oven to 375°F (190°C).

In a large pot, cook the lasagna noodles according to package instructions. Drain and set aside.

In the same pot, heat olive oil over medium heat. Add the diced onion and sauté until translucent, about 5 minutes. Stir in the minced garlic and cook for another minute.

Add the chopped spinach, sliced mushrooms, diced zucchini, and bell pepper to the pot. Sauté until the vegetables are tender, about 8-10 minutes. Season with dried Italian herbs, salt, and pepper. Remove from heat and set aside.

In a mixing bowl, combine ricotta cheese, egg, and half of the mozzarella cheese. Mix until well blended.

In the prepared baking dish, spread a thin layer of marinara sauce at the bottom. Place four lasagna noodles over the sauce.

Spread half of the ricotta mixture over the noodles, followed by half of the vegetable mixture. Layer on a third of the remaining marinara sauce and sprinkle with a third of the remaining mozzarella cheese.

Repeat the layering process starting with another four lasagna noodles, the remaining ricotta mixture, the rest of the vegetable mixture, another third of marinara sauce, and another third of mozzarella.

Top with the final four lasagna noodles, the last of the marinara sauce, mozzarella, and sprinkle with grated Parmesan cheese.

Cover the dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 15 minutes until the cheese is bubbly and golden.

Let the lasagna cool for 10 minutes before slicing. Garnish with fresh basil before serving.