In a large pot, combine 6 cups of low sodium chicken stock, 2 boneless skinless chicken breasts, 1 whole onion (halved), and 2 stalks of celery. Bring to a vigorous boil over medium-high heat, then reduce to a simmer. Cover and cook for 45–60 minutes until the chicken is cooked through and tender, reaching an internal temperature of 165°F.

Once the chicken is fully cooked, carefully remove it from the pot and let it cool slightly on a cutting board. Shred the chicken using two forks, pulling apart the meat into bite-sized pieces, and set aside. Strain the broth through a fine mesh sieve to discard the vegetables, returning the savory liquid to the pot.

In a large mixing bowl, whisk together 2 cups of all-purpose flour, 1 tablespoon of baking powder, and 1 teaspoon of salt until well combined. Add in 1/4 cup of cold butter, cutting it in until the mixture resembles coarse crumbs. Gradually stir in 3/4 cup of buttermilk until just combined; avoid overmixing.

On a floured surface, roll out the dumpling dough to about 1/8-inch thickness using a rolling pin. Cut the rolled dough into squares or rectangles, around 2 inches wide, and arrange them on a floured plate.

Return the strained broth to a gentle boil over medium heat. Carefully drop the prepared dumplings into the bubbling broth one at a time, ensuring they don’t stick together. Reduce the heat, cover the pot, and let the dumplings simmer for 15–20 minutes, or until fluffy and cooked through.

Once the dumplings are cooked, stir in the shredded chicken into the pot. Season with salt and pepper to taste, and heat through for an additional 5 minutes. Serve warm in bowls.