In a large pot with a lid, heat oil over medium heat. Add onions and cook until they begin to soften and turn translucent around the edges, about 5 minutes.
Add garlic and red pepper flakes and cook until garlic begins to turn golden and fragrant, about 1 minute. Stir in tomato paste and cook, watching closely, until the paste begins to stick and caramelize on the bottom of the pan, 1 to 2 minutes.
Stir in chicken broth and crushed tomatoes, scraping the bottom of the pot as you go making sure to dislodge any cooked-on bits.
Cover and bring to a simmer, adjusting heat as necessary. Simmer for 8 minutes. Add pasta, basil, and oregano, and cook, covered, until pasta is al dente, 10 to 12 minutes. Stir in cooked chicken and parmesan and heat until chicken is warmed through and parmesan is melted.
Add salt and pepper to taste.
Ladle into bowls and top each bowl with 1/4 cup of mozzarella cheese. Serve and enjoy!