Potatoes au gratin layer thin raw potato slices with cheese and a warm mixture of cream, milk, butter, and garlic. The dish needs a covered bake long enough to soften the potatoes, followed by an uncovered finish for the top. A browned surface is not enough on its own: test a center slice with a knife before serving. The measured batch makes six side portions and rests briefly before it is scooped.
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Why This Recipe Works
Thin, even slices help potatoes au gratin cook at the same pace. Potato starch contributes body to the cream mixture without a separate flour roux. A covered first stage holds moisture around the raw slices, and the final uncovered stage allows the surface cheese to color.
This formula has one cup each of cream and milk. The milk lightens the mixture while the cream keeps it richer than a milk-only bake. Heating that liquid gently before pouring it over the layers gives the dish a more consistent starting temperature.
Ingredients for Potatoes Au Gratin
Use four large potatoes, roughly two pounds total, and slice them about one-eighth inch thick. A mandoline can help, but use its guard and keep fingers away from the blade. Peeled Russet or Yukon Gold potatoes are suitable choices.
For potatoes au gratin, grate two cups of a melting cheese such as Gruyère or cheddar. Keep one cup for the middle and one for the top. The optional half cup of breadcrumbs is added with the top cheese after the potatoes soften, so it is not exposed through the whole covered bake. Nutmeg remains optional.
Main Ingredients
- 4 large potatoes, thinly sliced (about 2 pounds total, sliced 1/8 inch thick)
- 1 cup heavy cream
- 1 cup milk
- 2 cups shredded cheese (such as Gruyère or cheddar) (divided: 1 cup in the layers, 1 cup added near the end)
- 2 tablespoons butter
- 2 cloves garlic, minced
- Salt and pepper to taste
- 1/2 teaspoon nutmeg (optional)
- 1/2 cup breadcrumbs (optional, for topping)
How to Make Potatoes Au Gratin
Heat the oven to 375°F and lightly grease a shallow two-quart baking dish. Melt the two tablespoons of butter in a saucepan, then cook the minced garlic briefly until fragrant. Add the cream and milk with salt, pepper, and optional nutmeg. Warm over moderate heat without bringing it to a rolling boil.
Arrange half the sliced potatoes in the dish, scatter one cup of cheese over them, and add the remaining potatoes. Pour the warm cream mixture across the layers. The slices should sit close together rather than in a loose heap, with liquid able to flow between them.
Cover tightly with foil and bake potatoes au gratin for about 60–75 minutes, checking the center with a thin knife. If it still meets resistance, reseal the dish and continue; thickness, dish depth, and oven accuracy all affect the time. Once the slices are tender, remove the foil, add the reserved cup of cheese and optional breadcrumbs, and bake about 10–15 minutes more until the top is golden.
Let the dish stand for 10 minutes before portioning. The sauce settles slightly as it stops bubbling. If the topping darkens before the center softens, cover it again rather than increasing the heat and hoping the potatoes catch up.
How to Serve
Serve potatoes au gratin as six side portions with a roast, grilled vegetables, or a simple main course. A broad spoon can lift the softened layers without shredding them. Carry the hot dish on a stable heatproof surface, since the cream can bubble near the rim during the final baking stage.
Storage
Refrigerate leftover potatoes au gratin within two hours and use within three to four days. Keep portions in shallow covered containers. Reheat covered until the center reaches 165°F, then uncover briefly if you want to dry the topping. The sauce may look thicker or less smooth after refrigeration; this is different from potatoes that were left undercooked.
Follow FoodSafety.gov cooking temperatures.
Tips and Variations
Do not soak the freshly cut slices for a long period before layering; rinsing away surface starch changes the sauce thickening. If preparing ahead, the simplest option is to bake the dish fully, cool it promptly, and reheat a measured portion when needed.
Potatoes au gratin made with thicker slices needs more time than this thin-slice method. A deep narrow pan also slows the center. Use a shallow dish and check actual tenderness instead of shortening the covered stage because the cheese has already melted.
Frequently Asked Questions
Why are my potatoes au gratin still firm?
The slices may be too thick or the covered bake too short. Continue covered until a knife passes through a center slice easily.
Do I need flour in the sauce?
No. This formula relies on cream and potato starch rather than a separate flour-based cheese sauce.
When do I add breadcrumbs?
Add the optional breadcrumbs with the reserved top cheese after the potatoes are tender.
Can I use cheddar instead of Gruyère?
Yes. Choose a cheese that melts well and grate it before assembling the dish.
Why should the casserole rest?
A ten-minute rest lets bubbling slow and helps the layers and sauce settle before serving.
More Recipes to Try
- Creamy Mushroom Scalloped Potatoes
- Crock Pot Scalloped Potatoes
- Oven Roasted Potatoes with Garlic Powder
- Green Bean and Potato Casserole
Potatoes Au Gratin
Ingredients
Main Ingredients
- 4 large potatoes, thinly sliced about 2 pounds total, sliced 1/8 inch thick
- 1 cup heavy cream
- 1 cup milk
- 2 cups shredded cheese (such as Gruyère or cheddar) divided: 1 cup in the layers, 1 cup added near the end
- 2 tablespoons butter
- 2 cloves garlic, minced
- Salt and pepper to taste
- 1/2 teaspoon nutmeg (optional)
- 1/2 cup breadcrumbs (optional, for topping)
Instructions
- Set the oven to 375°F. Grease a shallow 2-quart dish and slice about 2 lb potatoes evenly, approximately 1/8 inch thick.
- Melt butter, briefly sauté garlic, and warm cream plus milk with seasoning and optional nutmeg; avoid a rolling boil.
- Layer half the potatoes, 1 cup cheese, then remaining potatoes. Pour in the warm liquid and cover tightly.
- Bake covered 60–75 minutes or until a center slice is easily pierced. Extend the covered stage if necessary.
- Scatter the second cup cheese and optional breadcrumbs on top; bake uncovered another 10–15 minutes until golden.
- Stand 10 minutes before dividing into six side portions.
