Cook the penne pasta in salted boiling water until al dente. Reserve ¼–½ cup of pasta water, then drain.
Season the chicken with salt, pepper, and Italian seasoning.
Heat olive oil in a large skillet over medium-high heat. Cook the chicken for 5–7 minutes until golden and nearly cooked through. Transfer to a plate.
Reduce the heat to medium. Add the garlic and sauté for 30–45 seconds until fragrant.
Pour in the chicken broth and heavy cream, scraping up any browned bits from the pan.
Stir in the sun-dried tomatoes and simmer gently for 4–6 minutes.
Mix in the Parmesan cheese until melted and smooth.
Add the cooked penne and chicken back to the skillet. Toss until evenly coated.
Stir in the spinach and cook until wilted.
Taste and adjust the seasoning. Add a splash of reserved pasta water if needed to loosen the sauce.
Serve immediately with extra Parmesan and fresh basil if desired.