1. Season the chicken with salt and black pepper. In a deep skillet, melt butter over medium heat or heat olive oil and brown the chicken pieces. Add minced garlic and sauté for an additional minute.
2. Stir in uncooked penne pasta and chicken broth, scraping up browned bits from the bottom. Cover and bring to a boil over medium-high heat, then reduce to medium-low and simmer for about 8 minutes, stirring every 2 minutes, until pasta is tender and most of the broth is absorbed.
3. Add milk or cream, cream cheese, and pesto, stirring and cooking until the cream cheese melts and the sauce is creamy. Stir in Parmesan cheese and adjust seasoning as needed.
4. If using, add fresh spinach and sun-dried tomatoes, cooking until the spinach wilts.
5. Finish with a sprinkle of freshly cracked black pepper, red pepper flakes, lemon zest, and fresh basil leaves before serving.