Make classic turkey gravy by melting 2 tablespoons of butter in a saucepan and browning the turkey neck and giblets. Add 1 chopped onion, 1 sprig each of parsley, sage, rosemary and thyme. Add 1 bay leaf. Pour in 8 cups of chicken broth, and simmer for two hours. Discard the bay leaf, strain the broth and set aside. After the turkey roasts, make a roux with flour and butter. Add the broth and drippings from the turkey.
Make a giblet broth by browning the neck and giblets in 2 tablespoons of melted butter and then simmering them with 1 chopped onion, 1 bay leaf, 1 sprig each of parsley, sage, rosemary, and thyme. Add in 8 cups of chicken broth, and allow them to simmer while the turkey roasts. Strain the broth and discard the herbs.
Make a turkey roux by combining 1/2 cup of turkey fat from the roasting pan with 1/2 cup of flour. If there isn't enough fat, use an equal amount of butter. Place the fat into a saucepan over medium heat. Sprinkle the flour over the fat, and cook until the flour browns. Pour in the broth mixture, whisking to prevent lumps. Pour in 1/2 cup of pan juices. Stir until the gravy reaches the desired thickness.