Boil rotini in salted water until al dente (8–10 min). Reserve 1 cup pasta water. Drain and set aside.
Toss chicken with olive oil, garlic powder, onion powder (optional), Italian seasoning, salt, pepper, and 2 tbsp Parmesan.
Sear chicken in batches over medium-high heat, 3–4 min per side, until golden and cooked through. Set aside.
In same skillet, lower heat, melt butter, and sauté garlic for 1–2 min until fragrant.
Add cream and broth. Simmer 3–5 min. Stir in mozzarella and ½ cup Parmesan until smooth. Season to taste.
Add rotini and chicken to sauce. Toss gently. Add pasta water if needed to loosen.
Top with parsley and extra Parmesan. Serve hot.