Poached Chicken:

1 (3-4 pound) chicken (cut into 8 pieces)
8 cups water
1 teaspoon Kosher salt
1 bay leaf
1/4 teaspoon whole black peppercorns
1 onion (quartered)
1 stalk celery (cut into large pieces)
1 carrot (cut into large pieces)

Scalloped Chicken Casserole:

1 tablespoon unsalted butter (for greasing)
1 loaf day-old white bread (crumbled into pieces like stuffing)
3 cups reserved poaching liquid
1 cup celery (chopped)
1/2 cup onion (chopped)
2 large eggs (slightly beaten)
1 teaspoon poultry seasoning
2 teaspoons Kosher salt
1/4 teaspoon freshly ground black pepper
poached chicken

For the Poached Chicken: Place the chicken in a large Dutch oven and cover with water.
Add salt, bay leaf, black peppercorns, onion, celery, and carrot.
Bring to a light simmer over medium heat.
Once liquid starts to simmer reduce to low-heat and cook until the juices run clear once pierced in the meatiest part,
about 10-12 minutes.
Remove chicken to a bowl and allow to cool.
Strain poaching broth to use later, discarding aromatics.
Once chicken is cool enough to handle, remove the chicken from the bones and chop the skin and meat into coarse pieces.
Discard the bones.
For the Scalloped Chicken: Preheat the oven to 350ºF. Grease an 8x11-inch baking dish with butter.
In a large bowl, add the crumbled bread, 3 cups of poaching liquid, celery, onion, eggs, poultry seasoning,
salt and pepper and stir to combine.
In the baking dish, alternate layers of chopped chicken and bread mixture, ending with the bread mixture.
Bake for 1 to 1 1/2 hours or until golden brown on top and bubbling. Shield the dish with foil if it gets too dark.

Note:
Try cooking the chicken in the slow cooker.
Add all poaching ingredients to the slow cooker and cook on High for 6 to 7 hours or until chicken is cooked through and very tender.