Clean any extra fat from the chicken. Slice it into pieces ( or in half like I did,) Place into a large dutch oven.
Add in the celery, carrot, onion, garlic, parsley and chicken stock. Place the lid on the Dutch oven and place into the oven.
Cook in the oven for 2 2-12 hours until the chicken is completely cooked and has reached a temperature of minimum 165°F).
Remove the Dutch oven from the oven.
Using a slotted spoon or tongs, remove the chicken and vegetables from the Dutch oven and place in a bowl or plate to the side.
Take 1/2 cup of the chicken broth that is left and set to the side for now and let cool.
One you can safely touch the chicken, remove the meat from the bones and set aside. Discard the bones.
Take the reserved broth and whisk the cornstarch into the mixture.
Place the Dutch oven on your stove burner on medium-high heat. Bring the remaining broth to a low boil. Whisk in the cornstarch mixture quickly to thicken the broth. You can add more cornstarch if you want it really thick, adjust to your liking.
Add the chicken and vegetables back into the Dutch oven and reduce the stove heat to low. Simmer for another 10 minutes.
In another bowl, stir the remaining 2 cups of Bisquick™ mix and the milk together until completely combined and formed into a sticky, soft dough.
Drop the biscuit dough by large tablespoonfuls onto the hot chicken mixture. I like to drop it onto areas that have liquid in order for the biscuits to not be dried out.
Place the lid back on the Dutch oven and cook for 10 minutes. Take off the lid and continue cooking for another 5-7 minutes until the biscuits are done.
A lot of recipes don't cover the dumplings with a lid and this is a mistake! Steam the dumplings for 10 minutes and then take off the lid and let the tops dry off somewhat. The dumplings will be light, puffy and tender!