Start by prepping your vegetables. Dice 1 ½ celery ribs, 1 carrot, ½ yellow onion, 1 small russet potato, and ½ red pepper into small pieces, about ¼ to ½ inch in size. Set them aside.
Heat a Dutch oven or large soup pot over medium-high heat and add 3 tablespoons of olive oil. Once the pan is hot, add the diced celery, carrot, onion, potato, and red pepper. Sauté for about 5 minutes, or until the vegetables start to soften. This step helps to release the natural sweetness of the veggies.
Next, add the drained and chopped tomatoes (14 oz can), 1 tablespoon parsley, 1 tablespoon oregano, 2 tablespoons minced garlic, and ½ teaspoon red pepper flakes. Stir the mixture well to coat the vegetables with the seasonings. The garlic and herbs give the soup its rich, Italian-inspired flavor.
Pour in 5 cups of water and 2 cups of chicken broth. Stir everything together and bring the soup to a boil over medium-low heat. Once it reaches a boil, reduce the heat and partially cover the pot. Let the soup simmer for 1 hour. This will allow the flavors to meld and the vegetables to soften completely.
After simmering for an hour, use a potato masher to gently mash some of the vegetables at the bottom of the pot. This step helps thicken the soup and creates a velvety texture while still keeping some chunks of veggies for heartiness.
Now, add 2 cups of shredded chicken to the soup and simmer for an additional 30 minutes. The chicken will absorb the flavors of the soup while adding protein to make it a filling meal.
While the soup is simmering with the chicken, cook 2 cups of ditali pasta according to package instructions. Drain the pasta and set it aside.
Right before serving, add the cooked pasta into the soup and stir to combine. Ladle the soup into bowls and, if desired, top each serving with freshly grated Parmesan for an extra layer of flavor.