Make sausage and herb seasoning.

Preheat oven to 160°C/140°C fan-forced.

Discard the neck from turkey. Rinse the turkey under cold water. Pat dry inside and out with absorbent paper. Fill neck cavity with some of the reserved seasoning and secure skin over opening with toothpicks. Fill large cavity with remaining reserved seasoning. Tie legs together with string. Tuck wing tips under the turkey.

Place the turkey on an oiled wire rack in a flameproof baking dish. Dip the muslin in the melted butter, fold the muslin over the turkey. This keeps the turkey moist while cooking. Cover with foil. Place the stock in base of dish. Bake turkey 3 hours.

Remove the foil and muslin from the turkey, brush with pan juices and sprinkle with salt. Bake turkey and seasoning balls, uncovered, a further 30 minutes or until browned and cooked through. Remove the turkey from the dish; stand, covered with foil, 30 minutes.

Reserve the juices from the turkey in a jug. Skim fat from top of juices; reserve ¼ cup fat for gravy. Add a few ice-cubes to the jug, then remove and discard ice-cubes along with solidified fat.

Make port gravy.

Serve turkey with seasoning balls and gravy.

In large frying pan, heat oil; cook onion, leek and garlic, stirring, until soft. Cool 10 minutes. Squeeze meat from sausages into large bowl. Add onion mixture, herbs, breadcrumbs and a little salt and pepper; mix well. Reserve a third of the mixture. Roll remaining mixture into 16 balls, roll each in a piece of prosciutto. Place balls on an oiled baking tray, refrigerate until required.

Place same baking dish over medium heat with the reserved fat. Add flour and cook, stirring, until flour is well browned. Remove from heat, stir in port; return to heat and cook, stirring, until mixture boils. Stir in 2 cups (500ml) of the pan juices and enough of the stock for desired consistency. Cook, stirring, until mixture boils and thickens. Strain gravy into large jug.