Season the Chicken: In a medium bowl, combine the diced chicken with salt, Italian seasoning, pepper, and crushed red pepper flakes. This step is crucial for building flavor in your chowder. Make sure to toss the chicken until it's evenly coated with the seasonings, allowing each piece to absorb the flavors before cooking.
Sear the Chicken: In a large Dutch oven over medium heat, heat olive oil until shimmering. Add the seasoned chicken and cook for 3-4 minutes, stirring occasionally, just until lightly browned on the outside. You're not trying to cook the chicken through at this point, as it will finish cooking in the soup. Using a slotted spoon, transfer chicken to a bowl and set aside. This partial cooking helps seal in the juices while creating flavorful browned bits on the bottom of the pot.
Sauté the Aromatics: In the same pot, add the diced onion. Cook for 4-5 minutes, until softened. Stir in the garlic and cook for 1 more minute. This builds the aromatic foundation of your chowder, allowing the onion to become translucent and sweet while ensuring the garlic releases its flavor without burning.
Create the Broth Base: Slowly pour in the chicken broth, making sure to scrape up any browned bits from the bottom of the pot. These bits contain concentrated flavor that will enhance your chowder. The slow addition helps incorporate everything smoothly.
Add the Dairy: Stir in the heavy cream and whole milk, whisking until smooth. The combination of these dairy products creates the perfect creamy base for the chowder, providing richness and body without being too heavy.
Cook Pasta and Chicken: Add uncooked pasta and the partially cooked chicken to the pot. Bring to a gentle simmer and cook uncovered, stirring occasionally, for 10–12 minutes until pasta is tender and chicken is fully cooked to an internal temperature of 165°F. Cooking the pasta directly in the broth allows it to release starch, which helps thicken the chowder naturally.
Add the Cheese: Reduce heat to low. Stir in the Parmesan and mozzarella until melted and smooth. The low heat prevents the cheese from separating or becoming stringy, while allowing it to incorporate fully into the creamy broth, adding depth of flavor and additional thickness.
Serve: Serve warm, garnished with extra Parmesan and chopped parsley. The fresh herbs add color and a bright contrast to the rich soup, while the additional Parmesan intensifies the savory flavor profile.