Make the apple and herb stuffing: Melt the butter in a saucepan, add the onion, and cook gently for a few minutes, until softened.
Remove from the heat, leave to cool slightly, then stir in the apple, bread crumbs, egg,parsley, thyme, lemon zest, and salt and pepper to taste.
Leave to cool completely.
Put the parsley and thyme sprigs into the cavity of the chicken, add the lemon and onion, if using, and season with black pepper.
Truss the chicken if desired.
Spoon the stuffing into the neck end of the chicken, secure the skin flap over the stuffing with a smalll skewer, and pat into a rounded shape.
Put any leftover stuffing into a small ovenproof dish.
Rub the softened butter over the chicken breast and season with salt and pepper.
Place the chicken, breast side down, in a roasting pan.
Cook in a 375* oven for about 1 1/2-2 hours.
Turn the chicken over when lightly browned.
Continue cooking, basting every 20 minutes.
Cook any leftover stuffing with the chicken for the last 40 minutes of cooking time.
Test the chicken: insert a skewer into the thigh-the juices will run clear when the chicken is cooked.
Transfer to a warmed serving platter and keep warm while you make the gravy.
Remove the stuffing from the neck cavity and transfer to a serving dish with any leftover stuffing.
Carve the chicken and serve with the gravy.
Gravy: Tilt the roasting pan, and spoon off all but 1 tbls.
of the fat that rises to the surface, leaving behind the cooking juices.
Put the roasting pan on top of the stove.
Add the flour and cook over medium heat for 1-2 minutes, stirring constantly with a whisk or metal spoon to dissolve any browned bits on the bottom of the pan.
Pour in the stock and bring to a boil, stirring constantly until the gravy thickens.
Simmer for 2 minutes, then taste for seasoning.
Strain into a warmed gravy boat and serve immediately.
Giblet Stock: In a stockpot or large saucepan, cook the giblets until lightly browned.
Stir in 1 quart water.
Bring to a boil, skimming off any scum that forms on the surface.
Add 1-2 quartered unpeeled onions, 1 chopped carrot, 1 chopped celery stalk, 1 bouquet garni, and a few black peppercorns.
Simmer for about 1 hour.
Cool, cover, and keep in the fridge for 3 days or freeze for 3 months.
Strain before use.