To brine the turkey: 

Finely chop dehydrated apple chips with a knife, spice grinder, or blender until its consistency is fine like a powder.

Mix all ingredients for the dry brine and place in a small resealable jar or resealable freezer bag. This can be stored in an airtight container for several months.

With a paper towel, pat the turkey breast dry.

Using 1 tablespoon of dry brine per pound of turkey, evenly sprinkle over the entire breast and under the skin.  Place uncovered in the refrigerator overnight, or for at least 6 hours.

To roast the turkey:

After the turkey has been brined and you are ready to roast, preheat the oven to 325°F.

Rub the softened butter evenly over the turkey breast, paying attention to the outside of the skin and under the skin.

Place the turkey breast skin side up in a roasting pan fitted with a roasting rack, and pour chicken stock in the bottom of the pan.

On the middle rack, roast the turkey for 20 minutes per pound and start to check for doneness about 10 minutes before the cook time is up with an instant-read probe thermometer. If the chicken stock is drying out at this point, you can add ¼ cup more.

Once the thickest part of the turkey breast reaches an internal temperature of 160°F pull it from the oven and allow it to rest, covered with aluminum foil, for 15 to 20 minutes. The turkey will continue to cook once it is out of the oven to an internal temperature of 165°F without losing moisture.