Brown the meat

• Heat the olive oil in a frying pan and brown the ground beef until fully cooked, breaking it up with a spoon.
• Season with salt and pour in most of the marinara sauce, keeping some aside for the bottom of the dish.
• Let the meat sauce simmer for a few minutes.

Prepare the cheese mixture

• Beat the egg in a mixing bowl and stir in the ricotta and half of the parmesan.
• Chop the parsley and fold it in.

Layer the lasagna

• Spread a thin layer of marinara sauce over the bottom of the baking dish so the noodles don't stick.
• Alternate layers of lasagna sheets, meat sauce, cheese mixture and shredded mozzarella.
• Finish with a generous layer of mozzarella and the remaining parmesan.

Bake covered

• Cover the dish with foil and bake at 180 °C.
• Remove the foil for the last minutes so the cheese gratinates.

Rest and serve

• Let the lasagna rest before cutting so the layers hold together.
• Sprinkle with the remaining parsley and serve.