Preheat oven to 375°F (190°C).
In a saucepan, heat olive oil over medium heat. Add garlic and cook until fragrant.
Add spinach and cook until wilted. Set aside.
In a mixing bowl, combine ricotta cheese, salt, and pepper.
Spread a thin layer of marinara sauce on the bottom of a baking dish.
Layer lasagna noodles, ricotta mixture, spinach, marinara sauce, mozzarella, and parmesan. Repeat layers.
Cover with foil and bake for 30 minutes.
Remove foil and bake for an additional 15 minutes, until cheese is bubbly and golden.
Let lasagna cool for 10 minutes before serving.