Preheat the oven to 200C/gas mark 6. Season the chicken inside and out with salt and pepper. Put the herbs into the cavity. Rub butter all over the breast and legs.
For the stuffing, melt the butter in a pan. Add the onion, livers and thyme, season and cook over a medium heat for 2-3 minutes. Off the heat, mix in the breadcrumbs, parsley and seasoning. Either use to stuff your bird or cook separately in an ovenproof dish wrapped in foil for the last 30-40 minutes.
Put the chicken into a large roasting tin and roast in the oven, basting regularly and adding the livers to the roasting tin for the last 6 minutes or so. Test the chicken after 1 ¼ hours by inserting a skewer into the thickest part of the thigh. The juices should run clear; if not roast for a little longer.
Lift the chicken onto a warmed platter and rest in a warm place for 15 minutes. Sprinkle with some more chopped parsley and serve with the roasted livers, stuffing, garlic sauce and straw potatoes.
Baked new season garlic sauce:
Preheat the oven to 200C/gas mark 6. Wrap the garlic bulbs in foil and bake them in the oven for 1 hour. Unwrap and leave until cool enough to handle, then peel away any tough outer skin.
Put the garlic into a blender with the parsley, mustard, breadcrumbs and warm duck fat or chicken juices and blend until smooth. Add enough milk to give the sauce a thick pouring consistency and season with salt and pepper to taste. Serve with roast chicken.
Straw potatoes:
Using a mandolin with a shredding attachment or a sharp knife, cut the potatoes into long matchsticks, about 3mm thick. Wash them well in a couple of changes of cold water to remove the excess starch, then drain and pat dry on some kitchen paper.
Heat an 8cm depth of oil in a deep-fat fryer or other suitable deep, heavy pan to 120-140C. Deep-fry the potatoes in manageable batches (a couple of handfuls at a time) for 2-3 minutes, then remove with a slotted spoon and drain in a colander.
Increase the temperature of the oil to 160-180C and re-fry the potatoes with the garlic slices in batches, moving them around in the pan, until golden and crisp. Remove with a slotted spoon and drain on kitchen paper. Sprinkle with sea salt and serve immediately.
Alternatively, you can keep the straw potatoes warm, uncovered, on a baking tray in a low oven until ready to serve. They should stay crisp but if not you can briefly re-fry them in hot oil to crisp them up again.
The best way to cook a quality chicken is simply, and on the bone. Try varying the vegetables