Potatoes au gratin is that rare side dish that feels equally appropriate at a fancy dinner party and on a Tuesday night at home with the family. That is to say, it’s incredibly easy to make, wonderfully decadent, and everyone loves it—even if no one is quite sure what to call it (potato gratin, au gratin potatoes, scalloped potatoes, that cheesy potato dish…we could go on).
Pick up russet or Idaho potatoes for this recipe; their starchy flesh makes them the best potatoes for soaking up the creamy sauce, while their sturdy skins keep the thin slices from falling apart. When simmering the cream, make sure it’s over a gentle heat (if it over-reduces, it will break). Slowly infusing and blending the creamy sauce ensures garlic and fresh thyme flavor the dish from corner to corner.
It’s the cheese (and sometimes an addition of breadcrumbs) that differentiates a gratin from scalloped potatoes. The latter comprises spuds simply sliced and baked in cream, while this potato gratin recipe gets a generous topping of nutty Gruyère cheese and a touch of Parmesan.