Creating Creamy Spinach Mushroom Lasagna can be straightforward if you follow these simple steps:

1. Cook the Lasagna Noodles: Boil a large pot of salted water and cook the lasagna noodles according to package instructions. Drain and set aside.
2. Sauté Vegetables: In a skillet, heat olive oil over medium heat. Add diced onion and minced garlic, sautéing until translucent. Include sliced mushrooms and cook until browned. Finally, stir in chopped spinach until wilted. Season with salt, pepper, and Italian seasoning. Remove from the heat.
3. Mix Cheese Filling: In a mixing bowl, combine ricotta cheese, one cup mozzarella cheese, grated Parmesan cheese, and the egg. Mix until smooth and creamy.
4. Layer Ingredients: Preheat your oven to 375°F (190°C). Spread a thin layer of marinara sauce in the bottom of a 9×13 inch baking dish.
5. First Layer: Place three lasagna noodles over the sauce. Spread one-third of the cheese mixture on top, followed by half of the sautéed vegetables and one-third of the remaining marinara sauce.
6. Repeat Layers: Repeat the layering process twice, finishing with a final layer of noodles topped with marinara sauce and the remaining mozzarella cheese.
7. Bake: Cover the baking dish with aluminum foil and bake for 25 minutes. Remove the foil and bake for an additional 10-15 minutes until the cheese is bubbly and golden.
8. Cool: Allow the lasagna to cool for about 15 minutes before slicing. This will help it hold its shape.
9. Serve: Enjoy this delicious Creamy Spinach Mushroom Lasagna warm, garnished with additional Parmesan cheese if desired.

Following these steps will guide you in creating this incredible dish effortlessly.