Heat butter in a large pot over medium heat. Add diced onions, carrots, and celery. Cook until softened.
Season chicken pieces with salt and pepper. Add to the pot and cook until lightly browned.
Pour in chicken broth and bring to a simmer. Let it cook for 15-20 minutes until the chicken is tender.
In a mixing bowl, combine flour, baking powder, and milk. Stir until a thick dough forms.
Drop spoonfuls of the dumpling dough into the simmering stew. Cover and cook for 15 minutes until dumplings are light and fluffy.
Gently stir, adjust seasoning, and serve warm with fresh herbs on top.