1 quart milk
3 large garlic cloves, smashed
salt and pepper to taste
freshly grated nutmeg to taste
8 medium low-starch potatoes
unsalted butter for buttering the gratin dish
1 1/2 cups grated Gruyère cheese
1 1/2 pints heavy cream
1. Place the milk and garlic in a large, heavy saucepan. Season with salt, pepper, and a little nutmeg. Bring to a boil, and simmer for 15 minutes.
2. Preheat oven to 450°F.
3. Peel the potatoes, and slice thinly on a mandoline or plastic vegetable slicer. Place potato slices in hot simmering milk, and cook very gently for 10 minutes or so, or just until the potatoes begin to soften.
4. Immediately drain the potatoes in a colander (reserve milk for another use, if desired). Butter an oval gratin dish that measures about 12 inch x 10 inch. Place half the potato slices in the dish, neatly arranged, making sure to sprinkle every single layer of potatoes with a little salt, pepper, and nutmeg. When half the potatoes are placed, cover with half of the grated cheese. Place the second half of the potato slices, again seasoning with salt, pepper, and nutmeg. Top with the remaining half of the cheese, evenly spread out. Pour the cream over and around the potatoes.
5. Cover the gratin loosely (with a lid or with aluminum foil). Place in the oven, and cook for about 45 minutes, or until the cream has cooked away. Remove the lid, and place the gratin briefly under the broiler until it's brown and bubbly. Serve immediately.