1 Preheat oven to 190°C. Pat the chicken dry inside and out with kitchen paper. Combine the walnuts, cranberries, onion, sage and garlic in a bowl and mix well. Add the breadcrumbs, stock and butter, then season with salt and pepper and mix to make a stuffing.
2 Press the stuffing into the chicken cavity, then secure the opening with a skewer. Brush the chicken with olive oil and season generously with salt and pepper. Arrange in a roasting pan and bake for 1 hour 25 minutes, until the juices run clear when pierced at the hip.
3 Meanwhile, heat the sherry in a medium saucepan over a moderate heat and boil until reduced by half. Add the stock, then boil until reduced to 1½ cups. Put ½ cup of the mixture in a bowl with the celery salt and cornflour, whisk until smooth, then return to the saucepan and simmer until thickened. Carve the chicken and serve with the gravy and baked vegetables.