How to Make It
Preheat the oven to 450°. In a bowl, combine the cocoa, chile powder, cinnamon, sugar, 1 teaspoon salt and 1/4 teaspoon pepper. Stir in the oil and vinegar. Rub half of the paste all over the turkey; spoon the remaining paste into the cavity.
Set the turkey on a rack in a large roasting pan and cook for 5 minutes. Baste the turkey with some of the melted butter and add 3 to 4 tablespoons of the turkey stock to the pan.
Lower the oven temperature to 350° and roast the turkey for 1 1/2 hours. Lower the oven temperature to 250° and add a little more stock to the pan. Baste the turkey with the butter and roast for about 1 1/2 hours longer, or until an instant-read thermometer inserted in the thickest part of the thigh registers 170°. Transfer the turkey to a cutting board, cover loosely with foil and let rest for at least 30 minutes.
Pour the pan juices into a saucepan and skim off the fat. Set the roasting pan on a burner over moderately high heat. Add the remaining stock and bring to a boil, scraping up any browned bits.
Strain the stock into the saucepan and bring to a boil. Spoon the paste from the turkey cavity into the stock. Boil the stock until reduced to about 1 1/2 cups, about 10 minutes. Whisk in the flour mixture and simmer over moderate heat until thickened. Season the gravy with salt and pepper. Carve the turkey and serve hot or at room temperature with the gravy.