1. Make the beef sauce
Heat a little oil in a large pan and sauté the onion until soft. Add the garlic and ground beef, breaking it apart as it cooks. Cook until browned.
2. Add the tomatoes
Stir in the tomato paste, chopped tomatoes, oregano, basil, salt and pepper. Simmer for 15–20 minutes, allowing the sauce to thicken.
3. Layer the lasagna
Spread a little beef sauce over the bottom of a baking dish. Add a layer of lasagna sheets, followed by more beef sauce and béchamel. Repeat the layers until everything is used, finishing with béchamel.
4. Add the cheese
Top generously with mozzarella and Parmesan.
5. Bake
Bake at 180°C for 30–40 minutes, or until bubbling and golden on top. Let it rest for about 10 minutes before slicing.