Preheat oven to 180°C, 350°F, Gas Mark 4, 10 minutes before cooking. If using a frozen turkey, ensure it is thoroughly thawed and no ice crystals remain in the body cavity. Remove giblets if necessary. (Use giblets to make stock for gravy). Wipe the turkey inside and out with either a clean damp cloth or kitchen paper.
Stuff the neck cavity with your prepared stuffing and secure neck flap, firmly encasing the stuffing. Season the body cavity then place the onion and fresh herbs inside. Weigh the turkey and calculate the cooking time allowing 20 minutes per kg plus 90 minutes.
Place in a roasting tin and spread the breast and thighs with the softened butter and place the bacon over the top. Cover loosely with foil and cook in the preheated oven for calculated cooking time.
Blend the ingredients for the glaze together and 40 minutes before the end of cooking time, remove foil and the bacon, if used. Pour half the glaze over the breast. Continue to cook for the remaining time, pouring over the remaining glaze after a further 10 minutes. Baste occasionally until the turkey is cooked and the juice run clear when the thigh is pierced with a skewer. Add a little of the pan juices to the gravy.
Allow to rest for 15-20 minutes before carving and serve with roasted potatoes and parsnips, sprouts and carrots.
For the Whiskey Glaze