This Swiss-style potato au gratin layers thinly sliced potatoes with a gently seasoned cream sauce and nutty Gruyère, then bakes until tender beneath a golden, bubbling crust. It makes a cozy side dish for a holiday meal or a simple supper, and the covered-then-uncovered baking method cooks the potatoes through without sacrificing the browned cheese on top.
There are plenty of regional and family versions of potato gratin across Switzerland and neighboring Alpine areas; this version keeps the flavors straightforward and lets the cheese shine.
Ingredients
- 2½ lb Yukon Gold potatoes (1.13 kg), peeled or scrubbed well
- 1½ cups heavy cream (360 ml)
- 1 cup whole milk (240 ml)
- 8 oz Gruyère cheese (225 g), freshly grated
- 1 tbsp unsalted butter (14 g), softened, for the baking dish
- 1 garlic clove (about 3 g), peeled and halved
- 1¼ tsp fine salt (about 7 g)
- ¼ tsp freshly ground black pepper (about 0.5 g)
- ⅛ tsp freshly grated nutmeg (about 0.25 g)
Instructions
- Heat the oven and prepare the dish. Set a rack in the center of the oven and preheat it to 375°F (190°C). Butter a 9-by-13-inch (23-by-33-cm) baking dish. Rub the cut sides of the garlic clove over the base and sides of the dish, then discard the garlic or save it for another use. This leaves a subtle aroma without creating strong pieces of garlic in the finished gratin.
- Slice the potatoes evenly. Peel the potatoes if you prefer a smooth, classic texture; leaving the skins on is fine if they are clean and thin. Cut them crosswise into slices about ⅛ inch (3 mm) thick. A mandoline makes uniform slices quickly, but a sharp knife works too. Keep the slices close in thickness so they soften at the same rate. Avoid rinsing or soaking the cut potatoes: their surface starch helps the cream sauce cling and thicken.
- Warm and season the cream. In a small saucepan, combine the heavy cream, milk, salt, pepper, and nutmeg. Warm over medium-low heat for about 3 to 4 minutes, stirring once or twice, until steaming but not boiling. Remove it from the heat. Warming the dairy takes the chill off and helps the gratin heat evenly; boiling can cause the cream to foam or separate.
- Layer the potatoes and cheese. Arrange about one-third of the potato slices in the prepared dish, overlapping them slightly. Spoon over about one-third of the warm cream mixture and scatter on roughly one-quarter of the grated Gruyère. Repeat twice, finishing with the remaining cream and the remaining cheese across the top. Distribute the cream carefully so it reaches the corners; the potatoes should be mostly coated, though the top layer need not be completely submerged.
- Cover and bake until the potatoes are nearly tender. Cover the dish tightly with foil and bake for 40 minutes. Keep the foil from pressing into the cheese if possible. The covered stage traps steam, which cooks the potato slices gently before the top is exposed to direct oven heat.
- Uncover and brown the top. Remove the foil carefully, keeping your hands clear of the hot steam. Bake for another 25 minutes, until the top is golden in spots and a paring knife slides through the center potatoes with little resistance. If the top is browned before the potatoes are tender, loosely replace the foil and continue baking in 5-minute increments. If the potatoes are tender but the top is pale, use the broiler for 1 to 2 minutes, watching continuously so the cheese does not burn.
- Rest before serving. Take the dish out of the oven and let it stand for 10 minutes. This gives the cream and starch a chance to settle, making the gratin easier to portion while it is still hot. Check a central portion, not just the browned edges, for tenderness before serving.
Tips
- Choose a good melting cheese. Gruyère gives the dish its characteristic savory, nutty flavor and melts smoothly. If it is difficult to find, use a Swiss-style cheese such as Emmentaler, or substitute an equal amount of sharp white cheddar. Emmentaler is mild and pleasantly stretchy; cheddar tastes sharper and makes the result less traditionally Swiss-style. Pre-grated cheese can work, but freshly grated cheese usually melts more evenly.
- Keep the slices thin and even. Thick or irregular slices are the most common reason a gratin has a browned top but firm potatoes inside. Aim for about ⅛ inch (3 mm). If slicing by hand, take your time and make a small stack of slices before arranging them, rather than trying to cut every potato to the same speed.
- Do not skip the covered bake. Cheese can brown before the potatoes cook if the dish is uncovered for the full baking time. Foil protects the top while the potatoes soften in the hot cream; uncovering toward the end gives the cheese time to develop color. Every oven and baking dish behaves a little differently, so use the knife test rather than relying only on the clock.
- Use a suitable baking dish and allow for bubbling. A ceramic or glass 9-by-13-inch dish works well. Set it on a rimmed baking sheet if it is very full or you are concerned about spills. A wider, shallower dish will brown more quickly and may need less time, while a deep dish can take longer for the center potatoes to become tender.
Serving Suggestions
Serve the gratin hot, cut into squares or spooned out in generous portions. Its creamy texture and rich cheese flavor pair especially well with roast chicken, pork tenderloin, baked ham, or a simple steak. For a meatless meal, serve it alongside a crisp green salad with a sharp vinaigrette and a plate of roasted or steamed green vegetables, such as green beans, broccoli, or Brussels sprouts. The acidity and freshness balance the richness without requiring another heavy sauce.
For a larger menu, make the gratin one of the sides rather than the only starch. It fits comfortably on a holiday table with roasted vegetables and a straightforward main course. Let it rest for the full 10 minutes before serving, then spoon some of the creamy sauce from the edge over each portion. A little chopped parsley can add color, but it is optional and not needed for the flavor.
Variations
Use Emmentaler or a cheese blend: Replace the Gruyère with 8 oz (225 g) Emmentaler for a milder, slightly sweeter flavor. You can also combine half Gruyère and half Emmentaler to keep the nutty character while making the cheese flavor less pronounced. Avoid very fresh, high-moisture cheeses such as mozzarella as the main cheese; they can release excess liquid and do not give the same savory crust.
Add a little onion: Thinly slice one small yellow onion, about 4 oz (115 g), and tuck a few pieces between the potato layers. It softens as the gratin bakes and adds sweetness. Keep the slices thin so they cook in the same time as the potatoes, and do not add a large amount or the extra moisture may make the dish looser.
Make it with a lighter dairy mix: For a less rich version, replace ½ cup (120 ml) of the heavy cream with an additional ½ cup (120 ml) of whole milk. The result will be less lush and may set a little more softly, but it still works. Avoid replacing all the cream with low-fat milk, which can make the sauce thin and more likely to separate.
Add herbs: Stir 1 tsp (about 1 g) finely chopped fresh thyme leaves into the warm cream, or scatter 1 tbsp (about 4 g) chopped chives over the finished dish. Thyme gives the cream a gentle herbal note; chives add a fresh finish. Add herbs modestly so they complement rather than cover the cheese.
Storage and Reheating
Let leftover gratin cool briefly, then refrigerate it within 2 hours of baking in a covered, shallow container or in the covered baking dish. It keeps for 3 to 4 days in the refrigerator. For easier reheating, divide it into individual portions once cool, or cut only the amount you need and leave the rest covered.
Reheat a portion in a 350°F (175°C) oven, covered loosely with foil, until hot throughout; uncover it for the final few minutes if you want to refresh the browned top. A microwave also works for individual servings, though the cheese will not become crisp again. Reheat leftovers to 165°F (74°C), checking the center with a food thermometer. Do not repeatedly cool and reheat the whole dish. You can freeze portions in airtight freezer-safe containers for up to 2 months for best quality; thaw overnight in the refrigerator before reheating. The potatoes may be a little softer after freezing.
Frequently Asked Questions
Do I have to peel the potatoes?
No. Yukon Gold potatoes have relatively thin skins, so you can scrub them well and leave the skins on if you like a more rustic texture. Peeling gives the gratin a smoother, more classic appearance. Either way, slice them evenly and remove any eyes or blemishes.
Can I assemble the gratin ahead of time?
For the best texture and color, bake it soon after slicing and layering the potatoes. If you need to prepare ahead, assemble it, cover it, and refrigerate it for up to 1 day. The potatoes can discolor slightly and may absorb some of the cream; allow the chilled dish to sit out while the oven heats, then expect it to need additional baking time. Do not leave the assembled dairy dish at room temperature for more than 2 hours.
Why are my potatoes still firm?
They may have been sliced too thickly, packed into a deep dish, or baked in an oven that runs cool. Cover the dish again and continue baking in 5-minute increments, testing the center with a knife each time. Do not turn up the heat dramatically to rush the process, because the cream can boil over or the cheese can scorch before the potatoes soften.
Can I use a different potato?
Yes. Yukon Gold potatoes hold their shape while becoming tender and have a naturally creamy texture. Russets also work and soften readily, but the layers can be more delicate and may break apart when served. Waxy red potatoes hold their shape firmly; slice them thinly and check that the center is tender before taking the dish out of the oven.
Can I make this without Gruyère?
Yes. Emmentaler is a close Swiss-style alternative, while a good Alpine-style cheese or sharp white cheddar can also melt well. Each changes the flavor: Emmentaler is milder, and cheddar is sharper. Use the same weight of cheese and grate it yourself for an even melt.
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