In a large pot, melt butter over medium heat.
Add garlic and onion; sauté 3–4 minutes until softened and fragrant.
Pour in chicken broth and bring to a gentle simmer.
Stir in heavy cream and Parmesan until melted and smooth.
Add shredded chicken, thyme, parsley, salt, and pepper.
Simmer 10–12 minutes, stirring occasionally, until thickened.
Optional: Add spinach or mushrooms and cook 2–3 additional minutes.
Serve hot.