While the turkey is cooking, place the turkey backbone you removed (and giblets if you have them), one large rough-chopped carrot, one large rough-chopped celery stalk, and half an onion in a large saucepan with 4 cups of water.
Bring to a boil, then reduce to a simmer and allow to cook for about one hour.
Strain your turkey stock and discard the solids.
In a saucepan, melt 2 tablespoon butter over medium heat. Once the butter is melted, add one minced clove of garlic and one teaspoon of thyme. Cook for one minute.
Whisk in flour and apple cider, and continue whisking until the mixture is completely smooth and thickened.
Add 2 1⁄2 cups turkey stock and whisk to combine. Cook until your gravy is thick enough to coat the back of a spoon.
Taste and salt and ground black pepper as desired.
Carve your turkey, and serve it with the warm gravy.