In a baking dish, spread a layer of marinara sauce on the bottom. Layer 3 lasagna noodles over the sauce.
Spread half of the ricotta cheese over the noodles, followed by half of the spinach and mushroom mixture, topped with a layer of mozzarella cheese.
Repeat the layers: another 3 noodles, the remaining ricotta, the rest of the spinach and mushroom mixture, and more mozzarella. Finish with a final layer of marinara sauce and a generous topping of mozzarella cheese.
Cover the dish with aluminum foil and bake for 25 minutes. After 25 minutes, remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden.
Let it cool for a few minutes before slicing. Serve and enjoy!
Notes
Cook noodles al dente and let the lasagna rest before slicing for easier serving.