1. Preheat your oven to 180°C (350°F).
2. Peel the potatoes, wash them, and cut them into thin slices. Do not rinse them after cutting, as the starch helps bind the gratin.
3. Bring the milk to a boil with the pressed garlic, salt, pepper, and nutmeg.
Then add the sliced potatoes, reduce the heat, and let them cook for about ten minutes, stirring regularly to prevent the potatoes from sticking to the bottom.
4. Pour everything (potatoes + milk) into a gratin dish and add the cream.
Distribute small pieces of butter on top, reduce the oven temperature to 160°C (320°F), and bake for 1 to 1.5 hours. Your gratin will be better if it cooks slowly for a long time. Pierce the potatoes to check if they are tender.
5. The next day, if you have leftover gratin, place a few small pieces of butter (be careful not to use too much) on top and bake for 30 minutes to 1 hour (depending on the amount you have left) at 150°C (300°F). (gratins are always better the next day! :))