Prepare the chicken and broth:

1. Heat oil in a large pot over medium-high heat. Add the chicken pieces and sauté until browned on both sides. This browning step adds a lot of flavor to the stock.
2. Add the chopped onions, carrots, celery, broth, Italian seasoning, bay leaves, pepper, and salt to taste.
3. Bring to a boil, then turn the heat to low and simmer covered for 1 hour.
4. Strain the broth. Remove and debone the chicken. You should have 2 quarts of broth (8 cups). Add a little water if necessary.

Make the dumplings:

1. Combine flour, baking powder, salt, and butter with a fork or pastry cutter until the butter is mixed in and in small pieces.
2. Add the milk, little by little, and mix gently until combined.
3. Put the dough on a floured surface and knead a few times on until dough comes together.
4. Roll the dough out on a generously floured surface to about 1/8 inch thick. Sprinkle more flour on top of the dough. Cut the dough into 1 inch by 2 inch strips. A generous amount of flour will prevent the dumplings from sticking and will also help to thicken the broth.

To finish the soup:

1. Melt the butter in the large pot. Sauté the chopped carrot and celery for about 1 minute.
2. Sprinkle in the flour and stir to thoroughly coat the vegetables. Stir in the chicken stock and bring to a boil.
3. With the heat on medium-high, drop in the dumplings one by one, stirring occasionally so they don’t stick. Turn the heat to medium low, and cook until the dumplings are tender and cooked through, about 15 minutes.
4. Stir in the chicken and remove from heat.
5. Garnish with parsley, if desired.