The classic French potato gratin with sliced potatoes, cream, and good cheese has been my Easter potato dish for years. The ingredients are simple, its preparation requires almost no skill on the part of the cook, and yet nothing is more elegant or satisfying to eat.
Best of all, it can be made today, and reheats beautifully. When I’m doing that, I usually take it from the oven as soon as the potatoes are barely tender and the top is just beginning to brown. I let it cool completely, then cover and refrigerate it. Take it from the refrigerator and let it sit at room temperature for at least half an hour (an hour would be better), then reheat it a 375 degree oven until the top is golden brown and it’s bubbly at the center.
Don’t try to assemble this ahead with the idea that you can bake it tomorrow: the potatoes will oxidize and turn black, even coated with cream.
Classic Potato Gratin
Serves 8-10
2 large yellow onions, trimmed, split lengthwise, peeled, and thinly sliced
2 tablespoons unsalted butter
2 pounds russet potatoes, (“baking” potatoes, about 4 large)
2 cups (1 pint carton) heavy cream
2 tablespoons chopped fresh sage, thyme, or parsley, optional
2 ½ cups (8 ounces) grated Comté or Gruyère cheese
Salt and whole white or black pepper in a peppermill
Whole nutmeg in a grater
1. Position a rack in the center of the oven and preheat to 400° F. Generously butter a 3 quart gratin or 10x15 2½-baking dish. I generally use an old-fashioned Le Creuset enameled iron gratin; the one in the photograph is a classic white Revol rectangular casserole.
2. Put the butter and onions in a large skillet over medium heat. Sauté, tossing often, until tender and evenly colored a deep gold, about 10-15 minutes. Be careful not to let them scorch.
3. Meanwhile, peel and thinly slice the potatoes with a sharp knife, mandoline, or food processor fitted with a slicing blade. Put them into a large mixing bowl and add the onion, cream, herbs, if using, and 2 cups of the cheese. Season with salt, pepper, and nutmeg to taste and toss well.
4. Pour this into the prepared casserole, scraping the bowl with a spatula. Flatten and level the top with the spatula and sprinkle with the remaining cheese over it. Put it into the oven and reduce the heat to 375°. Bake about an hour and 15 to 30 minutes, or until potatoes are very tender and bubbly at the center and the top is golden brown. If it begins browning before the potatoes are tender, reduce the heat to 350°. Serve hot or warm.