Boil a large pot of water, then cook the lasagna noodles until al dente, as per package instructions. Drain and set aside.
In a pan, heat olive oil over medium heat. Sauté chopped onion and minced garlic until fragrant and translucent, about 5 minutes.
Add chopped spinach to the pan and cook until wilted, about 2-3 minutes. Remove from heat and let cool slightly.
In a mixing bowl, combine ricotta cheese, cooled spinach mixture, a pinch of nutmeg, and a beaten egg. Season with salt and pepper, then mix until smooth and creamy.
Spread a thin layer of marinara sauce in the bottom of a baking dish. Layer cooked noodles over the sauce, then spread a portion of the ricotta mixture over the noodles.
Repeat layering with noodles, cheese mixture, and sauce until all ingredients are used, finishing with a layer of marinara sauce on top.
Sprinkle shredded mozzarella and grated Parmesan evenly over the top layer of sauce.
Cover the baking dish with aluminum foil and bake in a preheated oven at 180°C (350°F) for 25 minutes, until bubbling around the edges.
Remove the foil and continue baking for an additional 10 minutes, until the cheese is melted, bubbly, and golden brown.
Take the lasagna out of the oven and let it rest for at least 10 minutes. This helps the layers set and makes slicing easier.
Slice into squares and serve hot, enjoying the cheesy, layered goodness with a spooky Halloween twist.
