Preheat the oven to 375°F (190°C). Lightly oil a 9×13-inch baking dish.

Cook lasagna noodles according to package directions until al dente. Drain and lay flat on a sheet to prevent sticking. If using no-boil noodles, skip this step.

Heat 1–2 tablespoons olive oil in a large skillet over medium heat. Add minced garlic and cook for 30 seconds until fragrant.

Add sliced zucchini and mushrooms; sauté for 4–6 minutes until they begin to soften.

Stir in chopped spinach and cook for 1–2 minutes until wilted. Season with salt, pepper, and a pinch of Italian seasoning. Remove from heat and set aside.

In a bowl, combine ricotta cheese with a pinch of salt, pepper, and 1/2 teaspoon Italian seasoning. Mix until smooth. Optionally stir in 1 beaten egg for firmer filling.

Spread a thin layer of marinara sauce over the bottom of the prepared baking dish.

Build the lasagna: layer noodles, a third of the ricotta mixture, a third of the sautéed vegetables, a light sprinkle of shredded mozzarella, and more sauce. Repeat two more times, finishing with a generous layer of mozzarella and a dusting of grated Parmesan on top.

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

Let the lasagna rest for 10–15 minutes before slicing.