Preheat your oven to 375°F (190°C).
Cook lasagna noodles according to package instructions until al dente.
In a skillet, heat olive oil over medium heat and sauté garlic until fragrant.
Add mushrooms, zucchini, and bell pepper, cooking until tender.
Stir in spinach and cook until wilted, then season with salt and pepper.
In a bowl, combine ricotta cheese with half the Parmesan and a pinch of salt.
Spread a layer of marinara sauce on the bottom of a baking dish.
Layer 3 lasagna noodles over the sauce, followed by half of the ricotta mixture.
Add half of the sautéed vegetables, a layer of mozzarella, and then more marinara.
Repeat the layers, finishing with noodles topped with remaining sauce and cheeses.
Bake for 30-35 minutes until bubbly and golden.
Let it cool for 10 minutes before serving.