Boil salted water. Cook penne 1 min less than package. Reserve 1 cup pasta water. Drain.
Heat olive oil in large deep skillet medium-high. Season chicken with salt, pepper, Italian seasoning. Sear 5-6 min until golden. Remove to plate.
Same skillet, medium heat. Add garlic, red pepper flakes, sun dried tomatoes. Cook 1 min. Scrape browned bits.
Pour in chicken broth, simmer 1 min. Pour in heavy cream, bring to gentle simmer (do not hard boil).
Sprinkle parmesan a handful at a time, stirring until melted.
Add pasta, chicken, spinach. Toss 1-2 min until spinach wilts. Add pasta water if too thick.
Taste, adjust salt/pepper. Serve in warm bowls with extra parmesan and basil.