In a large skillet over medium heat, add the ground beef and cook until browned, about 6-8 minutes. Stir occasionally and drain excess fat.

Transfer the browned beef to a slow cooker and add the marinara sauce and beef broth. Stir gently to combine and cover. Cook on low for 4-6 hours.

30 minutes before serving, break the uncooked lasagna noodles into quarters and add them to the slow cooker. Stir to evenly distribute.

After the noodles have cooked for about 15 minutes, stir in the ricotta cheese and half of the shredded mozzarella cheese until well blended.

Once heated through and noodles are tender, ladle soup into bowls and sprinkle with remaining mozzarella cheese. Serve hot.