What Is a Gratin? Why We Love This French Take on the Casserole

For a simple and inexpensive way to elevate vegetables, look to the French, who have been giving potatoes, squash, and other produce the royal treatment since, well, the days of French royalty. A gratin, a dish of layered vegetables, is their brainchild—and it's adaptable and delicious through all seasons.

While often misunderstood as just cheesy potatoes, the world of gratins is vast and varied. It's both a dish that you eat, and the name of the physical dish that you bake the gratin in. Once you master the slicing and timing, the ease and affordability of a gratin will push this classic into your regular rotation. 

What Is a Gratin?

Although the dish has grown immensely popular in the United States within the last century or so, the history of the gratin dates back further. You can depend on nearly every bistro in France to have gratin on their menu, but the now-ubiquitous dish first was born before the French Revolution. It came about in the southeastern province of Dauphin (hence, gratin dauphinoise), and it was typically served during great feasts and celebrations. Since then, it became popular across the entire country, and home cooks have since learned how to prepare it on a regular basis.

Many Meanings

While we've come to know the dish as sliced potatoes (or other vegetables)—thinly sliced and covered in a cream and cheese—the word "gratin" has a wide breadth of meaning. "The term gratin doesn't refer simply to a potato dish—it refers to the delicious crust that forms on top of a baked dish," says Anna Kovel, food writer and cookbook author. 

"Another meaning to refer to when we talk about le gratin is about a certain type of people," says chef Guillaume Ginther, executive chef at Le Gratin restaurant in New York. He says le gratin is a phrase that extends well beyond the world of cooking, and can also refer to VIPs or "la crème de la crème" in French society. 

Making Gratins at Home 

Making a delicious gratin at home first means overcoming a few misunderstandings—the primary one being that gratins are just cheesy potatoes. "You don't even need cheese to make a crust on it," says Ginther; at his restaurant, only a small amount of cheese is added, and it's mostly just for color. 

And with a dish so simple, those preparing gratin at home usually encounter only one challenge: properly cooking the potatoes or vegetables. "This can be avoided by poking into the center of the gratin with a fork to be sure it's tender all the way through before removing the dish from the oven," says Kovel.

For a foolproof gratin, it's helpful to keep a these tips in mind: 

• Slice your vegetables evenly to ensure they all cook at the same rate. A mandolin is a helpful tool here, but the importance is not necessarily on making them thin—just uniform. So a sharp chef's knife will also do the trick. 
• If you're mixing a variety of vegetables in one gratin, be sure you're using vegetables that cook similarly to each other, such as carrots and potatoes, or zucchini and eggplant. 
• A classic gratin dauphinoise calls for cream that covers your potatoes or vegetables. With this type of gratin, be sure to heat your cream mixture well before pouring it over the vegetables—hot cream will give the dish a head start in the oven. Use this opportunity to infuse your cream with plenty of flavor, using herbs and aromatics: garlic cloves, shallots, fresh thyme, and sage leaves are well suited for this purpose. 
• Layer potatoes or other sliced vegetables at a 45-degree angle (as opposed to vertical stacks) so the shingled slices have a chance to fully absorb the cream mixture. 
• After baking, a quick flash under the broiler will give the top of your gratin an enviable golden brown glow. But before diving in, be sure to let the dish rest for at least 10 minutes so that it will maintain its composure (and cool slightly) when you slice into it. 

Vegetable Variations 

While it's the famed potato gratin dauphinois that we typically picture, Kovel says that many other things can be "gratinéed." "I like to make a zucchini or summer squash gratin, with Parmesan on top," she says. Kovel grates or thinly slices her squash, and salts it before cooking to remove the excess water. "I also like to bake ripe tomato halves with herbs, breadcrumbs, and olive oil on top, and you could call that a gratin too."

Other foods that gratin well include winter squash, mushrooms, and even seafood. Ginther prefers a variation of the classic potato gratin that incorporates parsnips into the mix. "The gratin is sweeter and more unctuous, especially if you top it with a blue cheese cream," he says. 

The Gratin Baking Dish

What vessel is better for cooking a gratin than a baking dish that shares its name? A gratin dish is typically shallow and oval-shaped, with handles on each side for easy transport from the oven to the table. But it isn't your only option: "Even though a classic gratin dish is beautiful and useful, you can make a gratin in pretty much any dish that is ovenproof, such as glass, enamel, or earthenware. It can be square, round, or rectangular," says Kovel. What's most important, she says, is that the dish you use is shallow and has enough surface area to give it that golden crust it's famous for.