Preheat the oven to 180°C (350°F) and lightly grease a 1.5–2 liter (or equivalent) baking dish with Butter.
Peel and slice the Starchy Potatoes (Bintje or Russet) very thinly (2–3 mm) using a sharp knife or mandoline; keep the slices uniform so they cook evenly.
Cut one clove of Garlic in half and rub the cut side all over the greased dish to infuse a subtle garlic aroma; mince the remaining clove finely and set aside.
In a saucepan, warm the Heavy Cream together with the Whole Milk over low heat—do not boil—then stir in the minced garlic, a generous pinch of Sea Salt, a few grinds of Black Pepper, and a light grate or pinch of Ground Nutmeg. Heat until hot and fragrant, then remove from the heat.
Arrange a single layer of potato slices in the bottom of the prepared dish, slightly overlapping. Season lightly with salt and pepper. Repeat layering until all potatoes are used, pressing the layers down gently to compact them.
Pour the warm cream mixture evenly over the potatoes so the liquid just comes up near the top of the stacks. If desired, dot the surface with a few small pieces of the remaining butter for extra richness.
Bake uncovered for about 45–60 minutes, until the potatoes are completely tender when pierced with a knife and the top is golden and bubbling. If the top browns too quickly, tent loosely with foil for the last 10–15 minutes.
Remove from the oven and let the gratin rest for 10–15 minutes before serving so it settles and slices cleanly. Serve warm as a rich, creamy accompaniment to your main course.
