Potatoes Au Gratin

This classic potatoes au gratin recipe is one of my favorite Thanksgiving side dishes, and it’s also fitting for Christmas, a dinner party, or any meal that calls for something a little extra. It involves layering thinly sliced potatoes with heavy cream and grated cheese in a casserole dish, and then baking until the cream thickens and blankets the potatoes in a rich, creamy sauce. And while it’s certainly worthy of a special occasion, honestly, a pan of these potatoes makes any dinner feel like one.

Potatoes Au Gratin vs Scalloped Potatoes

Potatoes au gratin and scalloped potatoes are similar dishes, but there are a few key differences. Both are made with thinly sliced potatoes baked until tender, but au gratin potatoes typically include cheese and are known for their rich, golden-brown top. Scalloped potatoes traditionally don’t contain cheese and are often flavored with onions and baked in a milk or cream sauce thickened with a roux.

What You’ll Need To Make Potatoes Au Gratin

• Russet Potatoes: With their high starch content, russets soak up the cream beautifully and bake into soft, melt-in-your-mouth layers. They’re the best choice for this dish. Skip the Yukon Golds here—they won’t give you the same texture.
• Heavy Cream: The secret to the luscious, velvety sauce. You might be tempted to swap in milk or half-and-half, but don’t—this recipe really needs heavy cream to thicken properly.
• Parmigiano Reggiano: Adds a salty, nutty depth that melts right into the potatoes, creating incredible flavor and texture. Be sure to use true Parmigiano Reggiano. If you can’t find it, Pecorino Romano makes a great substitute.
• Salt, Pepper & Thyme: These simple seasonings bring everything to life—the thyme is optional but adds a subtle earthiness that pairs perfectly with the creamy potatoes and cheese.
• Jump to the printable recipe for precise measurements

How To Make Potatoes Au Gratin

Slice the potatoes: Slice the potatoes as thinly and uniformly as possible so they cook at the same rate. A mandoline works well, but a sharp knife is all you need. If a potato feels wobbly, cut a thin slice lengthwise and place it cut-side down on the cutting board to create a stable base.

Season the potatoes: Toss the slices thoroughly with salt and pepper so the seasoning is evenly distributed. Potatoes need a generous amount of salt to bring out their flavor, so don’t be tempted to skimp.

Assemble the gratin: Arrange the potatoes in overlapping layers in a buttered baking dish, distributing the cheese and cream evenly as you go. Don’t worry about making the layers perfectly neat, but try to keep them fairly even so the potatoes cook uniformly. Be sure to pour in all of the cream—it will thicken as the gratin bakes, creating the rich, velvety sauce.

Bake until golden: Bake the gratin until the top is deeply golden and a knife slides easily through the potatoes with almost no resistance. Don’t cover the dish with foil; baking it uncovered is what gives you that beautiful browned top. Let it rest for a few minutes before serving so the cream can settle and thicken around the potatoes.

Finish with a sprinkle of fresh thyme and serve hot, while the top is crisp and golden and the potatoes underneath are creamy and tender.

Potatoes au gratin are best baked just before serving, but you can do some of the work ahead. See the recipe card below for my make-ahead, storage, and reheating instructions. If you love this recipe, try my cauliflower gratin or Brussels sprouts gratin next.