How to Make It
Preheat the oven to 425°.
In a large bowl, using your hands, blend all of the stuffing ingredients thoroughly, breaking up any large pieces of sausage meat. Stuff the cavity and neck of the chicken; don't be afraid to pack the stuffing slightly so there are no air pockets. Tie the legs together with kitchen string. Tie the wings together behind the back. Rub the chicken with the butter and season generously with salt and pepper.
Place the chicken breast-side up in a shallow flameproof roasting pan. Add the neck to the pan. Loosely tent the chicken with foil and roast in the center of the oven for 30 minutes. Remove the pan from the oven and gently remove the foil. Baste the chicken thoroughly, re-cover with the foil and roast for 30 minutes longer, basting occasionally. Reduce the oven temperature to 375°. Remove the foil, baste again and roast about 1 1/2 hours longer, or until the juices run clear when a thigh is pierced and the stuffing reaches 165° on an instant-read thermometer.
Remove the roasting pan from the oven and immediately season the chicken generously with salt and pepper. Transfer the chicken to a platter and tilt it neck end down. (This heightens the flavor by allowing the juices to flow down through the breast meat.) Cover the chicken loosely with foil and let rest for at least 10 minutes or up to 30 minutes.
Remove and discard the chicken neck from the roasting pan. Place the pan over moderate heat and cook, scraping and stirring, until the liquid is syrupy, 2 to 3 minutes; do not let it burn. Spoon off and discard any excess fat. Add 1/2 cup cold water and bring to a boil. Reduce the heat to low and simmer until reduced to 3/4 cup, about 5 minutes. Season with salt and white pepper. Strain the sauce through a fine-mesh sieve and pour it into a sauceboat.
Carve the chicken and arrange it on a warmed platter. Spoon the stuffing into a warmed bowl and serve.