Roast turkey with chestnut stuffing and bread sauce

4.5kg turkey with giblets

For the giblet stock:

neck, gizzard, heart 

2 carrots, sliced

2 onions, sliced

1 celery stalk

bouquet garni

4 peppercorns

For the chestnut stuffing:

450g chestnuts

175g butter

350g onions, chopped

400g soft breadcrumbs

50g freshly chopped herbs (parsley, thyme, chives, marjoram, savoury, lemon balm) 

salt

freshly ground pepper

melted butter, to baste the turkey 

large sprigs of fresh parsley or watercress, to garnish

For the bread sauce:

450ml milk

110g breadcrumbs

2 onions, each stuck with 6 cloves

50g butter

salt

freshly ground pepper

110ml thick cream