Potato Gratins

Typically a gratin is a casserole of sliced, layered ingredients cooked in the oven. “Gratiner” means “to brown” or “to broil” in French so a browned top is essential, whether it’s crispy with breadcrumbs and cheese or just lightly golden from the heat of the oven reacting with the sugars and proteins in cream. A gratin dish is traditionally a shallow, oval-shaped baking dish ideal for its low sides which allow more air circulation and therefore more browning, but any shallow baking dish will do—we usually call for our favorite 9 by 13-inch number.

It’s true that gratins have a reputation for being very heavy and rich, and while the version we see most often on the holiday buffet may be a classic creamy one, gratins actually come in lots of styles and flavor profiles—they don't even have to be made with potatoes! Root vegetable gratins and those made with hardy produce like fennel and cauliflower are delicious alternatives, but when it comes to potato gratin you can still lighten things up: our Olive Oil Potato Gratin relies on chicken broth and fruity oil as the liquid, eschewing all dairy save for a sprinkling of Pecorino, and our Potato-Tomato Gratin goes a step further, adding juicy tomatoes and caramelized onions to the layers of spuds.

It sure does make it easier, but no, it’s not absolutely necessary. In general a mandoline is a handy kitchen tool, and well worth adding to your cupboard—we like a Benriner style slicer—but if you don’t have one on hand when making the gratin recipes in this class you can use a chef’s knife (and a ruler, and some care) to hand-slice the potatoes. See our video lesson on How to Slice Potatoes for Gratins for more.

Often not a whole lot! It depends on who you ask but some will say one dish always contains cheese, while others say a white, flour-thickened sauce is involved in the other. The bottom line (for us, anyway) is that while scalloped potatoes are pretty much always potatoes cooked in cream (or a creamy sauce), when it comes to gratins the sky’s the limit!

It depends on the gratin! In general we look to starchy baking potatoes or slightly waxier all-purpose potatoes, avoiding boiling potatoes like red bliss. Since starchier potatoes like russets have more, well, starch and thus more thickening power, we use them in gratins that have a lot of naturally watery ingredients, like the tomatoes in the Potato-Tomato Gratin in this class. A waxier potato like a Yukon gold will contribute less starch, but is denser and will hold its shape better. Whatever you use, don’t soak the potatoes in water after slicing—you’ll rinse away that precious starch and diminish the thickening power of either variety.