Melt butter in a pot. Add chicken and cook for 4-5 minutes. Add celery, carrots, and onions. Add thyme and season with salt and pepper. Add broth and simmer for 35 minutes until tender. 

Mix flour, salt, and baking powder. Add milk and parsley, mix well. Drop onto soup by spoonful; proceed as directed above. 

Drop dumplings into simmering soup and cook uncovered for 5 minutes. Cover the pot and cook for 5 minutes longer. Enjoy.