Trim any fat from the chicken and cut into 1-inch cubes; season with 2 teaspoons Italian seasoning, about 1/2 teaspoon kosher salt, and a pinch of black pepper; toss to coat.
Heat 1 tablespoon olive oil in a large deep sauté pan over medium-high heat until shimmering.
Add the chicken and cook undisturbed for about 2 minutes to brown, then add the diced shallot and continue to sauté, stirring often, until shallots soften and chicken is browned on all sides, about 2–3 more minutes.
Reduce heat to medium, add the minced garlic and cook 30–60 seconds until fragrant, taking care not to burn it.
Pour in 2 cups low‑sodium chicken broth and scrape up any browned bits from the pan; stir in the remaining Italian seasoning and 1/4 teaspoon crushed red pepper flakes (if using) and bring to a light boil.
Add 8 oz dry pasta, stir to submerge the pasta in the broth, then cover, reduce heat to medium‑low, and cook 10–13 minutes, stirring every 2–3 minutes, until the pasta is almost al dente.
Remove the lid and stir in 1/2 cup grated Parmesan and 1/2 cup heavy cream; stir until the cheese melts and the sauce thickens slightly. Taste and adjust salt and pepper as needed.
Remove from heat and serve garnished with freshly minced parsley if desired.