01 - Bring a large pot of generously salted water to a boil. Add rigatoni pasta and cook according to package instructions until al dente. Reserve 0.5 cup pasta cooking water, then drain and set aside.
02 - Heat olive oil in a large skillet over medium-high heat. Add chicken pieces and season with salt, black pepper, and Italian seasoning. Sauté for 5 to 7 minutes or until golden brown and cooked through. Remove chicken and set aside.
03 - Reduce heat to medium. In the same skillet, melt unsalted butter. Add minced garlic and cook while stirring for about 30 seconds until aromatic.
04 - Pour in chicken broth, scraping the bottom of the skillet to release browned bits. Simmer for 2 minutes to build flavor.
05 - Stir in heavy cream and simmer for 3 to 4 minutes, stirring occasionally until slightly thickened. Add grated Parmesan cheese and incorporate until sauce is smooth. Adjust consistency with reserved pasta water if needed.
06 - Return cooked chicken to the skillet and toss to coat in sauce. Add cooked rigatoni and mix until pasta is evenly coated. Simmer together for 1 to 2 minutes so flavors meld.
07 - Remove from heat. Sprinkle with chopped fresh parsley, additional Parmesan, and optional red pepper flakes. Serve immediately while hot.