Preheat oven to 200°C (375°F).
Using a small saucepan, combine cream, lemon peel, thyme, garlic, salt, pepper, and nutmeg.
Bring to a boil over medium heat, then set aside for at least 10 minutes.
Slice your potatoes thinly (about 1/8 of an inch).
Prepare your baking dish by generously greasing it with butter.
Arrange the sliced potatoes on the baking dish.
Remove the thyme, lemon peel, and garlic from the cream, and strain it.
Pour the cream into the potato slices.
Top your kartoffelgratin with grated cheese.
Place it in the middle of the oven for 40-45 minutes or until the top has turned golden.
Set aside for at least 15 minutes to cool.
Slice, serve, and enjoy your kartoffelgratin!