Whisk all the marinade ingredients together in a jug.
In a large bowl use half the marinade to coat the chicken. Leave to marinate for 1 hour in the refrigerator.
In a second bowl use the rest of the marinade to coat the potatoes.
Layer the potatoes in the bottom of an ovenproof gratin dish approximately 30cm x 22cm. Dot the chopped Black Garlic cloves amongst the potatoes.
Cover the potatoes with a layer of onion and a layer of peppers.
Pour over the chicken stock.
Place the chicken on top of the potato, onion and peppers. Season with Black Garlic Seasoning or salt and freshly ground black pepper. Cover the gratin dish with foil.
Bake in the preheated oven for 2 hours. Remove the foil and bake for a further 15 minutes or until the potatoes are tender.
To Serve: spoon on to a large platter or individual plates. Garnish with chopped fresh parsley.