While the turkey is cooking, make the gravy. In a large sauce pan, heat the cooking oil over high heat. When hot, add in the turkey neck and gizzards. Brown the turkey on one side, then flip. Add in the onion and garlic cloves and continue to cook until onions are softened, and the turkey is nicely browned. Pour in the stock, add in the fresh thyme and bay leaves. When boiling, turn heat to low, simmer for 30 minutes. Strain, discarding solids. You should have about 2 1/2 cups turkey stock.
In a clean sauce pan, over medium heat, add the butter. When just beginning to bubble, add in the flour. Whisking constantly, for 5-8 minutes, until dark blonde roux is formed. Pour in just 2 cups of the turkey stock (reserve the rest) and whisk to combine.
Season the gravy for salt and freshly ground black pepper. To thin the gravy, pour in a little more turkey stock. To thicken the gravy, let the gravy continue to cook and reduce. To thicken in a hurry: in a small bowl, combine 1 tablespoon cornstarch and 1/4 cup water, stir to make slurry. Pour this into the gravy and continue to whisk until thickened.
When the turkey is finished frying, remove the drippings pan. Use a large spoon to discard the first top layer of fat/oil. Underneath the oil, you should find very flavorful drippings. Stir a big spoonful of the drippings into your gravy.