Bring the cream and milk to the boil in a large pan with the bay leaves, nutmeg, one teaspoon of salt and plenty of freshly ground black pepper.
Add the potatoes, reduce the heat and simmer gently for about 10-15 minutes, stirring often, until the potatoes are just pierceable with a knife but not fully cooked.
Meanwhile, heat the oven to 180C/160C fan/gas mark 4 and rub a deep-sided baking dish (approximately 20 x 30cm) all over with the garlic clove, then grease with some butter.
Remove the bay leaves from the potato mixture and add the cheese. Spread half this mixture over the dish, then scatter over the grated chestnuts and top with the remaining potato mixture.
Dot with butter and cover with foil (try not to let the foil touch the top of the dish as this will inhibit the crust), then bake for 35-40 minutes, until the potatoes are cooked through.
Remove the foil, scatter with the hazelnuts and bake for a further 15-20 minutes, until the top of the dauphinoise is nicely coloured and the hazelnuts are golden brown.
Remove from the oven and allow to rest for at least 10 minutes before serving.