Preheat your oven to 180°C (350°F) and set out your baking dish.
Cook the lasagna noodles in salted boiling water until just al dente, about 8 minutes. Drain and set aside.
Heat olive oil in a large skillet over medium heat. Add diced onion and minced garlic, sauté until fragrant and translucent, about 3 minutes, filling your kitchen with a savory aroma.
Add ground beef to the skillet and cook until browned, about 7 minutes. Break it apart with your spatula as it cooks, and stir in tomato sauce, salt, pepper, and a pinch of chili flakes if you like some heat. Let it simmer for a few minutes until thickened.
In a bowl, mix ricotta cheese with squeezed-out spinach and a pinch of nutmeg. This creamy layer adds a vibrant green pop and subtle flavor to your lasagna.
Spread a thin layer of the meat sauce at the bottom of your baking dish. Layer with noodles, then spread a generous layer of the ricotta-spinach mixture, followed by a sprinkle of shredded mozzarella. Repeat these layers until all ingredients are used, finishing with a top layer of cheese.
Cover the assembled lasagna with aluminum foil, sealing the edges to trap moisture. Bake in the preheated oven for 25 minutes, until bubbling around the edges.
Remove the foil and continue baking for an additional 10 minutes until golden and bubbly on top. Keep an eye on it to prevent burning.
Let the lasagna rest for about 10 minutes before slicing. This helps it set up and makes serving easier and neater.
Slice into squares, serve hot, and enjoy the hearty, cheesy layers with a festive twist.
