Heat oven to 180 C. Grease a baking dish with butter.
Mix cream and milk in a small pot with onion garlic salt pepper and nutmeg. Warm until steamy.
Layer potatoes in the dish in tight rows. Pour a little warm sauce over the first layer and add a small handful of cheese.
Repeat the layers until all potatoes are in. Finish with sauce and the rest of the cheese.
Bake for 50 to 60 minutes until the top turns deep gold and a knife slides in with no push.
Let the gratin rest for 10 minutes. Cut and serve.