Cook the Lasagna Noodles: Bring a large pot of salted water to a rolling boil. Add the lasagna noodles and cook according to package instructions until al dente. Drain the noodles and lay them flat on a parchment-lined baking sheet to prevent sticking.
Sauté the Vegetables: In a large skillet over medium heat, warm the olive oil. Add the diced onion and sauté for 2-3 minutes until they become translucent and fragrant. Stir in the minced garlic and sliced mushrooms, cooking for about 5 minutes until the mushrooms are golden brown. Add the chopped spinach and cook just until wilted, about 2 minutes. Season the mixture with salt, pepper, and Italian seasoning, then remove from heat.
Prepare the Cream Sauce: In a medium-sized mixing bowl, combine the ricotta cheese, heavy cream, and half of the grated Parmesan cheese. Mix well until smooth and creamy, then season with salt and pepper according to your taste preference.
Layer the Lasagna: In a 9x13 inch baking dish, start by spreading a thin layer of marinara sauce on the bottom. Place 3 lasagna noodles over the sauce. Spread half of the ricotta cream mixture evenly over the noodles, followed by half of the sautéed mushroom and spinach mixture. Spoon 1/3 of the remaining marinara sauce over the top and sprinkle with a third of the shredded mozzarella cheese. Repeat the layering process: more noodles, the remaining ricotta mixture, the remaining vegetable mixture, more marinara sauce, and finish with the last layer of noodles on top.
Finish the Layers: Pour the rest of the marinara sauce over the top noodles, ensuring they are well covered. Then sprinkle the remaining mozzarella cheese and the remaining grated Parmesan cheese evenly across the top.
Bake: Preheat your oven to 375°F (190°C). Cover the baking dish with aluminum foil to prevent over-browning. Bake for 25 minutes. Remove the foil and continue baking for an additional 15 minutes, or until the cheese is bubbly and golden brown.
Cool and Serve: Once baked, remove the lasagna from the oven and let it cool for about 10 minutes before slicing. This resting time helps the layers set, making it easier to serve. Enjoy the lasagna warm, and for an extra touch, serve with a sprinkle of chopped fresh basil on top.
Notes
Let the lasagna cool for a few minutes before slicing for easier serving.