In a large pot over medium-high heat, combine the lean ground beef and ground Italian sausage. Cook for about 6-8 minutes, breaking them apart with a wooden spoon until browned and no longer pink. Drain excess fat and set meats aside, keeping drippings in the pot.

Add a splash of olive oil to the pot. Toss in the chopped yellow onion and sauté for 5 minutes until softened. Add minced garlic and cook for another minute, stirring frequently.

Stir in the tomato paste and allow it to caramelize slightly for 1-2 minutes. Pour in the marinara sauce and chicken broth, mixing well. Add red pepper flakes, parsley, oregano, basil, and cooked meats. Bring to a gentle boil.

Once boiling, add broken lasagna noodles. Reduce heat to medium and let it simmer uncovered for 12-15 minutes, or until noodles are tender yet slightly al dente. Stir in fresh spinach in the last few minutes of cooking.

In a separate bowl, combine ricotta cheese, shredded mozzarella, and grated Parmesan. Mix until creamy and uniform.

Ladle the hot soup into bowls, topping with a generous dollop of the cheese mixture. Garnish with fresh basil if desired.