For the turkey:
1 (12- to 15-pound) turkey
3 tablespoons kosher salt
1 small medium onion, peeled and quartered
1 small apple, quartered and core removed
6 sprigs fresh thyme
4 sprigs fresh rosemary
For the cola glaze (optional):
2 cups cane sugar cola (Classic Coke from the glass bottle)
1 cup packed dark brown sugar
2 tablespoons unsalted butter
Thaw the turkey, if frozen: Thaw the turkey in the fridge. For a 12- to 15-pound turkey, this will take about 3 days, estimating 5 hours of thaw time for each pound of turkey.
Day of roasting
Prepare the turkey: Remove the giblets and neck from inside the turkey's cavity. Set the turkey on a v-roasting rack inside a roasting pan. Liberally season the turkey inside and out with the salt. Fill the turkey's cavity with the onion, apple, and herbs. Position the bird breast-side down in the roasting rack. Let the turkey sit out at room temperature 2 hours before roasting.
Roast the bird: Arrange a rack in the middle of the oven (remove racks above it) and heat to 400°F. Roast the turkey for 30 minutes to darken and crisp the skin. Reduce the heat to 325°F and roast the bird for an additional 2 hours.
Make the glaze: While the turkey roasts, place all the glaze ingredients in a small saucepan. Bring to a simmer over medium heat and cook, stirring occasionally, until reduced by half, about 10 minutes. Remove from the heat and set aside to cool slightly.
Glaze and finish the bird: Begin checking the temperature of the turkey after 2 hours of roasting at 325°F. Use a basting or pastry brush to liberally coat the turkey with the cola glaze, being sure to get under the wings and legs. Use a probe thermometer to check the turkey's temperature in both the thighs and the breast, you want 165°F for the thighs and 160°F for the breasts.
Rest and carve: Remove the turkey from the oven and rest for 20 to 25 minutes before carving. Any pale spots on the breast can be brushed with additional glaze as needed.