In a large soup pot or Dutch oven, cook the ground beef and Italian sausage over medium-high heat. Season with salt and pepper. Once the meat is browned, drain the grease and set the meat aside.

Add olive oil to the same pot. Toss in the chopped onion and cook for about 5 minutes until soft and translucent. Stir in the minced garlic and cook for another minute until fragrant.

Add the tomato paste and mix it through the onions. Pour in the marinara sauce and chicken broth. Sprinkle in the red pepper flakes, parsley, oregano, and basil. Return the cooked meat to the pot and stir everything together.

Bring the soup to a gentle boil. Break the lasagna noodles into smaller pieces and add them to the pot. Lower the heat to medium and let the soup simmer until the noodles are tender, about 12 to 15 minutes. If using spinach, stir it in during the last few minutes of cooking.

In a small bowl, combine ricotta, mozzarella, and parmesan. Stir until creamy and well mixed.

Ladle the hot soup into bowls. Add a generous dollop of the cheese mixture on top and let it melt into the soup. Sprinkle fresh basil over each bowl for a final touch.