Bring a large pot of salted water to a boil. Add the penne and cook according to package instructions until al dente – usually about 10-12 minutes. Drain and set aside, reserving a little pasta water just in case you want to loosen the sauce later.
Heat the olive oil in a large skillet over medium-high heat. Add the diced chicken breast, garlic powder, red pepper flakes, salt, and pepper. Cook, stirring occasionally, until the chicken is cooked through and golden brown on all sides, about 6-8 minutes. Remove the chicken from the skillet and set aside.
In the same skillet, lower the heat to medium. Pour in the chicken broth and heavy cream, stirring to combine and scraping up any browned bits from the chicken. Add the Italian seasoning and bring the mixture to a gentle simmer. Let it cook for 3-4 minutes until slightly thickened.
Gradually stir in the grated Parmesan cheese until melted and the sauce is smooth. Taste and adjust seasoning with more salt and pepper if needed. Return the cooked chicken to the skillet and toss to coat with the sauce.
Add the cooked penne to the skillet and toss everything together until the pasta is evenly coated. If the sauce is too thick, stir in a splash of the reserved pasta water to reach your desired consistency.
Sprinkle freshly chopped parsley over the top for a pop of color and fresh flavor. Serve immediately with extra Parmesan on the side, if desired.