I love roast potatoes and you’ll always find them on my Christmas table. But, if you’ve got a big crowd for Christmas then this gratin is an exciting and quite luxurious way of serving potatoes. You could either make them instead of, or as well as, your roast potatoes.
Preheat the oven to 200°C/400°F/gas 6. Butter the inside of an ovenproof dish, around 30cm x 30cm, and at least 6cm deep.
Pour the milk and cream into a wide pan with the bay leaves and garlic. Bring to the boil, then simmer gently for a minute or two. Remove from the heat and season with salt and pepper.
Add the potatoes and most of the thyme leaves and stir well. Spoon into the gratin dish and shake to even everything out. Sprinkle with the Parmesan then cover with an oiled piece of foil. Bake for 45 to 50 minutes.
Meanwhile, fry the bacon in a little olive oil until crispy and golden. Add the remaining thyme and stir in the chestnuts. When your gratin is ready, remove the foil and spoon the bacon and chestnut mixture over the top. Pop it back in the oven for another 10 minutes until gorgeous and crispy on top.