Heat olive oil and butter in a large pot over medium-high heat.
Season chicken with salt and pepper, then add to the pot. Cook until browned on all sides, about 5-6 minutes. Remove and set aside.
In the same pot, add diced onion and cook until softened, about 3 minutes. Add garlic and cook for 30 seconds.
Pour in chicken broth, heavy cream, sun-dried tomatoes, Italian seasoning, and red pepper flakes. Stir well and bring to a boil.
Add pasta and cook according to package instructions until al dente.
Return chicken to the pot and stir in Parmesan cheese until melted and creamy.
Garnish with fresh basil before serving.