Cooking this lasagna is a labor of love that’s well worth the effort. Follow these steps for a dish that’s sure to impress:

1. Preheat your oven to 375°F (190°C).
2. Cook the lasagna noodles according to package instructions, then drain and set aside.
3. In a large skillet, heat olive oil over medium heat. Add the onion and garlic, sautéing until fragrant and translucent, about 3-4 minutes.
4. Add the mushrooms to the skillet and cook until they release their moisture and begin to brown, about 5 minutes.
5. Stir in the fresh spinach, cooking just until wilted. Season with salt, pepper, and oregano. Remove from heat.
6. In a medium bowl, combine ricotta cheese, egg, and half of the Parmesan cheese. Mix until smooth.
7. To assemble the lasagna, spread a thin layer of marinara sauce on the bottom of a 9×13 inch baking dish.
8. Layer 3 lasagna noodles over the sauce, followed by half of the ricotta mixture, half of the spinach and mushroom mixture, and a third of the mozzarella cheese.
9. Repeat the layers, finishing with a layer of noodles topped with the remaining marinara sauce, heavy cream, and the rest of the mozzarella and Parmesan cheese.
10. Cover the dish with foil and bake for 25 minutes. Remove the foil and bake for an additional 15 minutes, until the cheese is bubbly and golden brown.
11. Let the lasagna rest for at least 10 minutes before slicing. This allows the layers to set, making it easier to serve.