Place the chicken, onions, carrots, and celery in a large stock pot and cover with water. Bring to a boil, then reduce heat so water maintains a gentle simmer. Cook chicken for 1 hour or until cooked through (about 165 degrees).

Once chicken is done, remove from the broth and let cool. Remove chicken from the bone and shred into medium-sized pieces, discarding bones and skin.

Pour the chicken broth through a fine mesh sieve lined with cheese cloth, discarding vegetables. Reserve 6 cups of the broth for the dumplings. (You can refrigerate or freeze the rest to use in for another recipe.)

Mix flour, baking soda, and salt together in bowl. Cut butter into flour mixture with your fingertips until it resembles small peas.

Add milk — ¼ cup at a time, you may not need a full cup — and stir until a ball of dough just begins to form, being careful not to over-mix.

Roll out the dough onto floured surface. Roll about ¼ inch thick. Using a pizza cutter or sharp knife, cut dough into rectangles about 1 inch wide by 3 inches long. Place strips on wax paper and allow to harden up a bit, about 30 minutes.

In a large pot or dutch oven over medium-low heat, bring broth to a gentle simmer and drop in dumplings. Cover and allow to cook for 6-7 minutes.

Reduce heat to low and add chicken. Allow to cook until thickened, approximately 15-20 minutes, or longer. Season generously with salt and pepper.