Heat olive oil in a large pot over medium heat. Sauté onions, carrots, and celery until tender.
Add chicken broth, cooked chicken, salt, and pepper to the pot. Bring to a simmer.
In a separate bowl, combine flour, baking powder, salt, milk, and melted butter to form the dumpling dough.
Drop spoonfuls of dumpling dough into the simmering soup. Cover and cook for 15 minutes, or until dumplings are cooked through.
Serve hot and enjoy your comforting chicken and dumplings soup!