Season Chicken: Pat the chicken dry and season with salt, pepper, garlic powder, and half the Italian seasoning.
Sear Chicken: In a large pan over medium heat, heat olive oil and sear chicken for 5–6 minutes on each side until golden. Remove and set aside.
Cook Pasta: Boil pasta in salted water according to package instructions, minus 1 minute. Save 1 cup pasta water, then drain.
Start Sauce: In the same pan, melt butter. Sauté garlic for 30 seconds. Stir in flour and cook 1 minute.
Make It Creamy: Slowly whisk in chicken broth, then heavy cream. Simmer until thickened (about 3–4 minutes).
Add Flavors: Stir in parmesan, sun-dried tomatoes, remaining Italian seasoning, and chili flakes. Season to taste.
Combine: Slice chicken, return to pan with pasta. Toss well to coat. Use reserved pasta water to adjust consistency.