Combine chicken, broth, and water in a pot. Simmer 20–25 minutes until tender.
Remove chicken; mix flour, baking powder, salt, and pepper in a bowl.
Whisk milk and melted butter; add to dry mix until dough forms.
Add onion, carrots, celery, thyme, and garlic powder to broth; simmer 10 minutes.
Shred chicken and return to broth. Drop dough in spoonfuls.
Cover and cook 15–20 minutes until dumplings are fluffy.
Garnish with parsley and serve warm.
