Prepare the pasta: Bring a large pot of salted water to boil. Cook penne pasta according to package directions until al dente. Reserve 1/2 cup pasta water, then drain.
Season the chicken: Cut chicken breasts into uniform bite-sized pieces. Season with salt, pepper, and Italian seasoning.
Cook the chicken: Heat olive oil in a large skillet or pan over medium-high heat. Add chicken pieces and cook for 5-7 minutes, stirring occasionally, until golden brown and cooked through (internal temperature 165°F). Remove chicken and set aside.
Make the sauce base: In the same pan, add butter and minced garlic. Sauté for 1 minute until fragrant, being careful not to burn the garlic.
Create the cream sauce: Pour in chicken broth and bring to a simmer. Reduce heat to low and slowly add heavy cream, stirring constantly. Let simmer for 2-3 minutes until slightly thickened.
Add cheese: Gradually whisk in Parmesan cheese until melted and smooth. If sauce seems too thick, add reserved pasta water 1 tablespoon at a time.
Combine everything: Return cooked chicken to the pan along with the drained pasta. Add sun-dried tomatoes if using. Toss everything together until well coated with sauce.
Final touches: Taste and adjust seasoning with additional salt and pepper if needed. Remove from heat and garnish with fresh chopped parsley.
Serve: Serve immediately while hot, with additional Parmesan cheese on the side if desired.
