Preheat the oven to 165℃.
Pour the milk and the double cream into a saucepan. Add 40 g of the grated parmesan, nutmeg, garlic granules and chopped thyme.
Cook it over a medium heat until almost boiling. Then take it off the heat. Season to taste.
Meanwhile, use a mandolin to thinly slice the potatoes.
Layer the potatoes, standing up like dominoes all around an oven proof dish. I used a 22 cm round pie dish.
Pour the cream over the top, then sprinkle with the remaining parmesan.
Bake it in the oven for 55 minutes.
Turn the heat up to 200℃ and cook for a further 10-15 minutes or until it becomes crispy on top.
Leave it to stand for five minutes before serving.
