1. Melt butter in a large pot over medium heat. Add chopped onions, carrots, and celery. Cook for 5-7 minutes until vegetables are softened. Add minced garlic and cook for another minute.

2. Add chicken thighs and pour in the chicken broth. Bring to a boil, then reduce to a simmer. Cook for 25-30 minutes until chicken is tender.

3. Remove chicken and shred using two forks. Return shredded chicken to the pot.

4. In a bowl, mix 3 tablespoons of flour with a splash of water to make a slurry. Stir into the pot to thicken the broth. Simmer for 5-10 minutes.

5. In another bowl, mix 1 cup flour, baking powder, salt, and milk to form dumpling dough.

6. Drop spoonfuls of dumpling dough into the simmering broth.

7. Cover and simmer for 15 minutes. Do not lift the lid to ensure fluffy dumplings.

8. Season with additional salt, pepper, and thyme if desired. Serve hot.