Bake chicken in a covered dish at 350º until done through, or cook in the instant pot for 30 minutes. The chicken should release juices as it cooks, and you don’t want those to evaporate away!
When chicken is done, shred with forks, transfer to a 4 quart or larger pot, and set aside (skip these first two steps if you’re using pre-cooked chicken)
Melt butter in a skillet over medium heat
Chop carrots, celery, and onion
Sauté in melted butter until vegetables are crisp-tender
Peel (optional) and chop potatoes, and add to chicken pot
Add sautéed vegetables, Better Than Bouillon Concentrate, pepper, salt and basil
Add two cups of water
Place lid on pot, and simmer until potatoes are tender
Meanwhile, stir milk and cornstarch together
When potatoes are done, remove lid, and add milk mixture
Stir to combine, and continue simmering until thickened (2-3 minutes)