1. Preheat the oven to 200C.
2. To make the stuffing,heat a little olive oil in a frying pan. Add the onion and garlic and cook over a low heat for about five minutes or until the onion is soft. Remove from the heat and set aside to cool. Blanch the spinach in boiling salted water until just wilted,then drain and rinse under cold water. Squeeze the excess water from the spinach. Chop coarsely. Combine the onion mixture with the spinach,breadcrumbs,herbs,prunes,macadamia nuts and butter in a medium bowl. Add the eggs,season with salt and pepper and mix very well.
3. Gently put your fingers between the skin and breast of the bird working your way down to the thighs. Don't rush,you don't want to tear the skin.
4. Press the stuffing under the skin of the turkey on the breasts and legs,until it is firmly packed in. Rub the skin with plenty of oil and season the turkey inside and out.
5. Place the turkey in a large baking tray and roast for 30 minutes. Reduce the oven temperature to 150C and cook for four to five hours or until cooked. (The best way to ensure the turkey is cooked through is with a meat thermometer. If the bird is larger,add 20 to 30 minutes for every 500 grams over 7.6 kilograms. When cooked,the internal temperature of the breast should be 74C and the legs 80C.)
6. Reduce the oven temperature to 50C,cover the turkey with foil and allow it to rest in the oven for about 20 minutes.
7. To serve,remove the drumsticks,thighs and wings at the second joint. Slice the breasts into one to two-centimetre thick slices,being careful not to rip the skin. Place on a platter and drizzle with some juices from the baking tray,aged balsamic vinegar, a good extra-virgin olive oil, another little sprinkle of sea salt and a grind of fresh pepper.