In a large oven safe soup pot, heat the olive oil over medium heat and add the onion. Sauté the onion until soft, about 5-6 minutes.
Add the garlic, salt, Italian seasoning, pepper, and tomato paste.
Stir for a minute or 2 and then add the broth, tomatoes, and cheese rind, if using.
Bring to a boil and add the pasta. Return to a boil and reduce heat to a simmer. Cook until the pasta is about 2-3 minutes from al dente. Do not overcook or your pasta will be too soft when the soup is done. It will continue to cook as the soup cools.
Add the chicken and parmesan cheese into the soup and stir to combine.
Remove from the heat, remove the parmesan rind, and sprinkle the mozzarella cheese over the top gently to not let it sink. Put the pot (make sure it’s oven safe) in the oven and turn the broil on high. Broil until the cheese is melted, about 3-4 minutes. Keep a close eye on it so it doesn’t burn.
Remove from the oven and garnish with parsley and more parmesan, if desired.