Peel and chop the carrot, celery, onion and garlic. Measure out the 8 cups of liquid (stock plus cooking liquids).
Heat the butter and oil in a saucepan over medium heat. Add the neck and giblets and cook until the meats are cooked through and have taken on a bit of color.
Add the chopped vegetables and garlic, and sauté until the vegetables are caramelized, about 15 minutes. Stir occasionally to prevent sticking and burning. You may need to turn the heat down to low or medium-low.
Mix the apple juice and brandy together, and turn the heat up to medium-high. Add the juice mixture to the pan to deglaze, scraping up the brown bits on the bottom of the pan. Reduce until the juice evaporates to an essence (Approx. 5 minutes).
Add the 8 cups of liquid, peppercorns, parsley, thyme, poultry seasoning and bay leaf. Reduce heat to low and simmer, uncovered for one hour. Season lightly with salt and pepper. Strain this “quick stock” and set aside.
Remove turkey from roasting pan. Pour off pan drippings and reserve. Place roasting pan over high heat (straddling two burners, if necessary deglaze with white wine.
Skim all but 2-3 Tablespoons of the fat from the reserved pan drippings and return the drippings to the pan.
Sprinkle the flour into the pan and cook over medium-high heat, scraping and stirring constantly, for 2-3 minutes.
Pour in the quick stock and bring liquid to a boil over medium heat to thicken.
Taste and adjust seasonings.
Strain through a fine mesh strainer before serving.