Heat 3 tablespoons of the oil in a small heavy pan and add the onion.
Cover and sweat for 10 minutes or until soft and starting to caramelize,
then cool. In a bowl, combine the walnuts, orange zest, parsley,
cranberry sauce and egg, and season well with salt and pepper. Stir in
the cooled onion mixture, and put to one side.
Preheat the oven to 200°C/400°F/Gas mark 6. Gently ease up the
chicken skin and push in the stuffing. Reshape the chicken and put in a
large roasting tin.
Spread with the mustard and season with salt and pepper. Drizzle over
2 tablespoons of the oil and roast for 25–30 minutes, basting
occasionally. Leave to cool, reserving the roasting juices.
