In a large pot, cook ground beef and sausage over medium-high heat until browned. Season with salt and pepper, then drain and set aside.
In the same pot, heat olive oil over medium heat, add diced onion, and sauté for about 5 minutes. Add garlic and cook for another 1-2 minutes.
Stir in tomato paste, marinara sauce, red pepper flakes, parsley, oregano, basil, and broth. Return the cooked meat to the pot.
Bring the soup to a boil, then add broken lasagna noodles. Reduce heat and simmer, stirring occasionally, until noodles are tender. Add spinach, if desired.
In a small bowl, combine ricotta, mozzarella, and Parmesan cheese.
Serve soup hot with a dollop of the cheese mixture on top, and garnish with fresh basil. Enjoy!