Wash the turkey, taking care to remove any remaining feathers. Preheat the oven to 200 ºC. Use a needle to inject the sweet wine into the turkey breast, legs and thighs to stop them drying out in the oven.
Soak the prunes and stale bread in water and then add the finely chopped bacon and apple. Mix it all together, strain off the excess water and use the mixture to stuff the turkey. Truss by sewing up the opening with kitchen twine.
Sprinkle some salt and a little black pepper over the bird and pour the melted butter on top. Arrange on an oven tray with the sliced onion and roast for three hours (cover with tinfoil halfway through).
Leave to cool for 20 minutes when it comes out of the oven. Serve with salad or roast potatoes cooked on the same tray.