In your slow cooker, combine the finely chopped yellow onion, diced green bell pepper, and minced garlic. Stir in the tomato paste along with dried oregano, dried basil, salt, ground black pepper, and optional red pepper flakes. Pour in chicken broth, ensuring everything is mixed well. Set the slow cooker to high and cover, letting it work its magic for 4 hours.

While the soup base simmers, brown ground beef in a skillet over medium heat for about 5–7 minutes until thoroughly browned. Drain any excess fat and set aside.

After 4 hours, carefully lift the lid from the slow cooker and stir in the browned ground beef. Cover again and let it cook for an additional 2 to 4 hours on low.

Once your soup has simmered to perfection, add heavy cream and Parmesan cheese, stirring until fully blended. Allow to heat through for about 10 minutes.

After the cream and cheese have been incorporated, add mafaldine pasta, stirring well and covering. Cook for an additional 30 minutes or until the pasta is tender.

Ladle the warm soup into bowls, topping each serving with freshly shredded mozzarella.