Heat olive oil in a large skillet over medium-high heat. Season the chicken with salt and pepper, then cook for 3–4 minutes until lightly golden. Remove and set aside.
Add diced onion to the same pan and cook for 2–3 minutes until translucent. Add minced garlic and cook for another 30 seconds.
Stir in sun-dried tomatoes, Italian seasoning, and red pepper flakes. Cook for 1 minute to build flavor.
Pour in chicken broth, scraping any browned bits from the bottom. Add pasta and stir well.
Bring to a boil, then cover and cook for 8–10 minutes, stirring occasionally, until the pasta is almost al dente.
Return chicken to the pot and cook uncovered for 2–3 minutes until fully cooked.
Reduce heat to low, add heavy cream and lemon zest, and stir. Gradually mix in parmesan cheese until the sauce thickens.
Stir in most of the basil, then let rest for a few minutes before serving. Garnish with extra cheese and basil.
