Baking a Classic Potato Gratin

Every culinary repertoire should have a dish that is dead simple and yet has the cachet of being something special, the kind of dish that when you put it on the table, everyone says, "Oh, wow, I just love..." whatever it is. My dish is a classic French potato gratin, which takes about 15 minutes to get into the oven, is made from ingredients that you probably already have in your kitchen, and is the perfect complement to both "fancy" main dishes, like rack of lamb or beef tenderloin, and "homey" dishes, like roast chicken or meatloaf.

You'll find many versions of this dish, called gratin dauphinoise in French (pronounced gra-TAN doh-fee-NWAHZ); mine is a simple marriage of potatoes and cream, with a few seasonings and a sprinkle of cheese. After 40 minutes in the oven, this gratin becomes so much more than just potatoes and cream—textures change, flavors develop, and the thing transforms itself into a nutty, rich, satin-textured whole that's way more than the sum of its fairly commonplace parts.

Make it Your Way: Use the Potato Gratin Recipe Maker to create a gratin recipe with all your favorite flavors, add-ins, and toppings.

The potatoes are low-fat, but the cream's not

I think Yukon Golds are perfect for this dish. Actually, I think Yukon Golds are perfect for a lot of dishes. They have a sweet, nutty flavor, and they're a great balance between being starchy —so they get soft and creamy when cooked—and being waxy (like a boiling potato)—so they keep their shape better than baking potatoes. But if you can't find Yukons, do use a starchier potato, which should be labeled baking potato, Idaho, russet, or russet Burbank. You want the potato to have some starch to mingle with the cream during cooking, and you want the slices themselves to have a buttery-soft final texture.

As for the cream, let me say this: if you're looking for a low-fat dish, this is not it. This dish is full of cream, and no, there's no substitute. There are versions of potato gratin that use half-and-half, or even stock, but for the kind of dish that makes your guests keep saying, "Oh, I think I'll just have one more little slice," and makes you keep thinking, "Oh, I hope they don't eat the whole thing—I want some for breakfast," you need real cream, and lots of it. And there's a technical reason for using cream, too: when a milk product is cooked with an acid (potatoes are quite acid), it can curdle unless the butterfat content is 25% or higher.

I put a delicate layer of shredded Gruyère cheese on top of the dish. Notice I say delicate, because if the cheese is too coarsely shredded or if the layer of it is too thick, it can get tough and separate from the underlying potatoes. So use the fine holes on your grater and don't be tempted to load up on the cheese. Imported Gruyère, Emmental, or Comté will have the perfect nutty-mellow flavor.

A steady base makes for an even slice. If the potato wobbles as you cut, flip it onto a wider side.

While this dish is extremely easy to assemble, you do have to pay attention to slicing the potatoes. They must be really uniform and really thin—uniform because you want them all to cook at the same rate so each bite is evenly tender, and thin because thin is the key to the magic of this dish. Think of it this way: if you have two pounds of thinly sliced potatoes, it means you have lots of slices and therefore lots of surfaces for starch to come out of and for cream to go into. The intersections of cream and potato are what make the texture so wonderful, and with more slices you have more intersections in every bite.

So since perfect slices are critical, making this dish will be your motivation to sharpen your knives. Or to buy a mandoline slicer, if you've always wanted one. Fortunately, getting perfectly round slices isn't important, because we're not going for a perfect overlapping look. That means that you can use the trick in the photo above left to keep the potato steady as you slice all the way to the end.

No need for neat layers. Just shake the dish to settle the slices.

The only other word of caution about making this dish is be careful of cooking it in too hot an oven or for too long. While you must cook it long enough for the alchemy to take place, if you go too far, the cream will separate and the butterfat will start to break out. Watch for this as the potatoes go through distinct stages of cooking: first you'll see lots of mad bubbling of cream, which makes you say, "This can't possibly be right; it's swimming in cream." Next, the amplitude of the bubbling decreases, but the frequency stays high because the cream is getting thicker; the top of the gratin also starts to brown. The last phase is small bubbles, thick cream, and just the first few drops of yellow butterfat appearing around the edges of the pan. Take the dish out of the oven the moment you see any butterfat.

The other key to this dish is not to serve it right away—give it a good 15-minute rest; it will still be hot on the plate, but the cream will form a more clingy cloak around the potatoes. This is actually a very important thing to know about a lot of food—roasts, steaks, lasagne, fruit pies. Letting the dish cool and relax a bit before serving it lets liquids redistribute, textures even out, sauces thicken up, and flavors come to the fore.

The last thing to know about this dish is that it's delicious the next day, cold, with maybe just the chill taken off by a few minutes in the oven or a few seconds in the microwave. Serve a wedge of cold gratin dauphinoise with a simple green salad dressed in a fairly sharp vinaigrette, ideally made with walnut oil, and congratulate yourself on being such a good cook.