Heat the olive oil in a large, deep oven-safe skillet over medium heat. Add the onions, carrots, and garlic. Cook for about 5 minutes, stirring occasionally, until softened.

Increase the heat to high. Add the ground beef and cook, breaking it apart with a wooden spoon, until browned. Drain excess grease if necessary.

Stir in the tomato paste, bay leaves, passata, 2 cups of the beef broth, salt, and pepper. Pour the broth into the empty passata jar first and shake it gently to collect any remaining tomato before adding it to the skillet.

Bring the sauce to a strong simmer and cook uncovered for 10 minutes. If the mixture looks especially thick, add more broth as needed.

Reduce the heat to low. Break the lasagna noodles in half and submerge them in the sauce one at a time, arranging them in different directions so they don’t stick together.

Cover the skillet and cook according to the lasagna noodle package directions, or until the noodles are tender. This will generally take about 18–20 minutes. Stir or gently separate the noodles once or twice during cooking, if needed.

Remove and discard the bay leaves. Arrange the mozzarella slices over the top.

Place the skillet under the broiler for approximately 3–5 minutes, watching closely, until the cheese is melted, bubbly, and golden brown.

Let the skillet lasagna rest for 5–10 minutes before serving.