01 -
Preheat oven to 375°F (190°C). Grease a 9×13-inch baking dish with cooking spray or olive oil.
02 -
Fill a large pot with salted water and bring to a boil. Add lasagna noodles and cook until al dente. Drain and set aside.
03 -
Heat a large skillet over medium heat and add 2 tablespoons of olive oil. Cook finely chopped onion until translucent, about 3–4 minutes. Add minced garlic and cook for 1 minute.
04 -
Add sliced mushrooms, dried thyme, salt, and pepper to the skillet. Cook until tender and the liquid has evaporated. Add chopped spinach leaves and cook for 2–3 minutes until wilted. Remove from heat.
05 -
Spread a thin layer of marinara sauce over the bottom of the prepared dish. Place a layer of lasagna noodles, spread some ricotta cheese, add the mushroom-spinach mixture, sprinkle with mozzarella and Parmesan, and repeat layers ending with sauce and cheese on top.
06 -
Cover the dish with aluminum foil and bake in the preheated oven for 25 minutes. Remove foil and bake for an additional 10 minutes or until the cheese is melted and bubbly.
07 -
Let the lasagna cool for 5–10 minutes. Garnish with fresh basil leaves and serve.