In a large skillet, heat a bit of oil over medium heat. Add the chopped onion and garlic, and sauté until soft. Add ground beef and cook until browned. Stir in crushed tomatoes, tomato paste, oregano, basil, salt, and pepper. Bring to a simmer and let cook for about 20 minutes.

Prepare the Cheese Mixture

In a bowl, combine ricotta cheese, egg, half of the mozzarella, half of the Parmesan, and chopped parsley. Mix well until smooth.

Assemble the Lasagna

Preheat oven to 180°C (350°F). Layer the bottom of a baking dish with a thin layer of Bolognese sauce. Place 4 lasagna noodles on top, then spread half of the cheese mixture over the noodles. Add another layer of Bolognese sauce, followed by another 4 noodles. Repeat the layers, finishing with a layer of Bolognese sauce. Top with remaining mozzarella and Parmesan.

Bake

Cover the baking dish with foil and bake in the preheated oven for 25 minutes. Remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden.

Serve

Let the lasagna sit for 10 minutes before slicing. Serve warm, garnished with extra parsley if desired.