Gather chicken, butter, onion, celery, carrots, garlic, chicken broth, milk, flour, baking powder, salt, pepper, and parsley
Season chicken with salt and pepper
Melt butter in a large pot over medium heat
Cook onion, celery, and carrots until softened
Add garlic and cook briefly
Add chicken and broth
Bring to a boil, then reduce to a simmer
Cook until chicken is fully cooked and tender
Remove chicken, shred it, and return it to the pot
Stir in milk if desired
Mix flour, baking powder, salt, and milk or water to make dumpling dough
Drop spoonfuls of dumpling dough into the simmering broth
Cover the pot and cook without lifting the lid
Simmer until dumplings are cooked through
Stir in parsley
Serve hot