If you want to brine your turkey, try dry brining as follows. If you want to skip this, be sure to salt the bird well when rubbing it with the flavored butter if it did not come pre-salted. Trim the neck of the turkey and reserve for gravy making or soup making later. Dry brine the turkey by salting the top and bottom of the turkey with 1% salt by weight (this works out to about 4.5 grams salt for every pound of turkey). Rub the baking soda over the surface of the skin. Place salted bird, uncovered in the refrigerator overnight (this allows the skin to dry out, producing more crisp skin).
Place the oven rack on its lowest position and set a baking stone or baking steel on it. Preheat the oven to 500°F and allow the oven and stone to preheat for at least 45 minutes before adding turkey. Place a V-rack into a rimmed baking sheet lined with foil and set aside.
If you did not dry brine the bird, dry the skin as well as you can with paper towels. Carefully separate the skin from the turkey breast using your hands, making sure not to tear the skin. Combine the spice butter ingredients and stir until smooth. Spread this mixture all over the breast meat under the skin.
Place turkey on the V-rack in the baking sheet and transfer to baking stone. Turn the oven down to 300°F and roast the turkey until it is golden brown and deepest part of breast registers 145°F, 2 to 4 hours total (start checking at 2 hours, especially if you have a smaller bird), depending on the weight of the bird, basting occasionally with drippings from bottom of roasting pan.
While the turkey is baking, combine all glaze ingredients in a small pot and bring to a boil. Boil until reduced by half and slightly thickened. Set aside.
Remove turkey from oven and brush all over with half the glaze. Return the turkey to the oven and continue to roast, checking temperature every 5 minutes, until a thermometer inserted into thickest part of breast measures 150°F, 15–25 minutes. The temperature will continue to rise as the bird rests. Transfer turkey and V-rack to a platter and let rest 1 hour.
Add a cup of chicken stock to the roasting pan and scrape up any browned bits. Pour the stock and any drippings into a small pan and set aside. Do not clean the baking pan.
Increase oven temperature to 450°F. Return the turkey in the V-rack to the pan. Brush the turkey with the second half of the glaze and roast, checking often as the glaze can burn, until turkey is deep golden brown and skin is shiny and crisp, about 5 minutes. Transfer to a clean platter and let rest 30 minutes before carving.
While the turkey rests, pour any more accumulated drippings into the reserved pan of stock/drippings and bring to a boil along with the gelatin. Reduce volume by half, until slightly thickened. Serve as a sauce with turkey.