Preheat your oven to 180°C (350°F). Gather all ingredients and set your baking dish nearby.
Cook the lasagna noodles in a large pot of boiling salted water until just al dente, about 8-10 minutes. Drain and set aside, avoiding overcooking.
In a pan, heat olive oil over medium heat. Add chopped onion and minced garlic, sauté until fragrant and translucent, about 5 minutes, filling your kitchen with a savory aroma.
Stir chopped spinach into the pan, cooking until wilted, about 2 minutes. Remove from heat and let cool slightly.
In a mixing bowl, combine ricotta cheese, sautéed spinach mixture, a pinch of nutmeg, and a beaten egg. Season with salt and pepper, then mix until smooth and well blended.
Spread a thin layer of marinara sauce in the bottom of your baking dish to prevent sticking.
Layer cooked noodles over the sauce, then spread a generous portion of the ricotta mixture over the noodles.
Pour more marinara sauce over the cheese layer, then repeat the layering process—noodles, cheese, sauce—until all ingredients are used, finishing with a sauce layer on top.
Sprinkle shredded mozzarella evenly over the top layer, then add grated Parmesan for a crispy, cheesy finish.
Cover the dish with aluminum foil and bake for 25 minutes, until bubbly around the edges. Remove the foil and continue baking for an additional 10 minutes until golden and bubbling.
Take the lasagna out of the oven and let it rest for at least 10 minutes. This allows the layers to set and makes slicing easier.
Slice into squares, revealing the cheesy, layered interior with a slight crust on top. Serve hot and enjoy your spooky, cheesy Halloween lasagna!
