Preheat your oven to 375°F (190°C).
Cook the lasagna noodles according to package instructions until al dente, then drain and set aside.
In a large skillet, heat olive oil over medium heat. Add chopped onion and minced garlic, sautéing until the onion is translucent.
Add diced zucchini, red bell pepper, and sliced mushrooms to the skillet. Cook for about 5-7 minutes until the vegetables are tender. Stir in the fresh spinach and cook until wilted. Season with oregano, basil, salt, and pepper. Remove from heat.
In a mixing bowl, combine ricotta cheese and egg, mixing until well blended.
Spread a thin layer of Alfredo sauce on the bottom of the baking dish.
Layer 4 lasagna noodles over the sauce, followed by half of the ricotta mixture, half of the vegetable mixture, a third of the mozzarella cheese, and a third of the Parmesan cheese. Repeat the layers again, finishing with a final layer of noodles and the remaining Alfredo sauce on top.
Sprinkle the remaining mozzarella and Parmesan cheese over the top layer.
Cover the baking dish with aluminum foil and bake in the preheated oven for 25 minutes.
Remove the foil and bake for an additional 20 minutes, or until the cheese is bubbly and golden.
Allow the lasagna to cool for 10 minutes before slicing and serving.