Sauté aromatics: In a large 6-quart Dutch oven or heavy soup pot, melt 3 tablespoons of butter over medium heat. Add the diced onion, celery, and sliced carrots. Cook for 6 to 8 minutes until vegetables begin to soften. Add minced garlic, poultry seasoning, thyme, bay leaves, salt, and black pepper; cook for 1 minute until fragrant.

Simmer chicken & broth: Pour in the 6 cups of chicken broth and nestle the raw chicken breasts into the liquid. Bring to a gentle boil over medium-high heat, then reduce heat to low, cover, and simmer for 20 minutes until the chicken reaches an internal temperature of 165°F (74°C) and is fork-tender.

Shred chicken: Remove the cooked chicken from the pot onto a cutting board. Using two forks, shred the meat into generous bite-sized chunks. Keep the pot simmering on low.

Make the dumpling dough: In a large bowl, whisk together 2 cups of flour, baking powder, and 1/2 teaspoon salt. Add cold cubed butter and cut in using a pastry blender or fingers until the mixture resembles coarse meal. Pour in the cold buttermilk, stirring with a fork just until a soft, shaggy dough forms (do not overwork).

Roll and cut dumplings: Generously flour a clean counter or pastry mat. Turn the dough out, gently knead 3 to 4 times into a smooth disc, and roll out with a floured rolling pin to about 1/8-inch thickness. Using a pizza cutter or sharp knife, slice the dough into 1.5x2-inch rectangular strips. Dust lightly with flour so they don't stick.

Drop dumplings and cook: Bring the Dutch oven broth to a steady low boil. Drop the dumplings one by one into the bubbling liquid, gently submerging them with a wooden spoon. The excess flour on the dumplings will naturally thicken the soup into a rich velvety gravy. Reduce heat to low, cover tightly with the lid, and cook undisturbed for 15 to 18 minutes until dumplings are puffed and cooked through.

Assemble and serve: Stir the shredded chicken and optional heavy cream back into the pot. Simmer gently for 2 to 3 minutes until warmed through. Discard bay leaves. Season with additional salt and plenty of cracked black pepper. Ladle into warm bowls and garnish with chopped fresh parsley!