Sides / Potatoes & sweet potatoes
Potatoes Au Gratin with Gruyère
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Thin potato layers, cream steeped with garlic and thyme, and Gruyère tucked between the layers, not just sprinkled on top. It bakes under foil, then browns and bubbles, and the corner pieces are the ones people fight over.
The short version
Steep cream with garlic and thyme, layer 1/8-inch russet slices with Gruyère in a buttered 9×13-inch dish, pour the cream over, cover with foil and bake at 375°F for 45 minutes. Uncover, top with Parmesan and bake 25 to 30 minutes more. Rest 15 minutes before serving.
What makes ours better
the tricks Nonna pretends she never taught me
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Steep the cream with garlic and thyme. A few minutes of warm cream pulls the flavor out of the garlic and herbs and spreads it through every layer, which raw garlic scattered between slices never does.
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Cheese in the layers, not just on top. Gruyère between the potatoes melts into the cream and makes the sauce taste like cheese all the way down. Parmesan on top is for the crust.
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Bake covered, then uncovered. Foil traps steam so the potatoes cook through gently without the top drying out. Taking it off for the last half hour browns the cheese.
What you need
the cast, in order of appearance
- Unsalted butter1 tablespoon
- Heavy cream2 cups
- Garlic2 cloves
- Fresh thyme4 sprigs
- Ground nutmeg1 pinch
- Russet potatoes2½ pounds
- Gruyère6 ounces
read it twice. buy it once.
Steps
nobody opens the oven door. looking at you, Dad.
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Heat the oven, butter the dish
Set a rack in the middle of the oven and heat it to 375°F. Butter a 9×13-inch baking dish, or any shallow 3-quart dish, with the 1 tablespoon of butter.
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Steep the cream
Combine the cream, garlic, thyme, salt, pepper and nutmeg in a saucepan. Heat over medium until small bubbles appear at the edge and steam rises, then take it off the heat and let it sit for 10 minutes. Fish out the garlic and thyme stems.
Don't let it boil hard. A rolling boil can break the cream.
About 10 min. Cook mode has a timer for this step.
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Slice the potatoes
Slice the peeled potatoes 1/8 inch thick with a mandoline or a sharp knife. Keep the slices as even as you can so they cook at the same pace. Don't rinse them; the surface starch thickens the cream.
Slice just before you assemble. Cut potatoes turn gray if they sit out for long.
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Layer with cheese
Arrange a third of the potatoes in the dish in overlapping rows, sprinkle with a third of the Gruyère, and repeat twice more. You should end with cheese on top. Pour the warm cream evenly over everything and press gently so the slices are mostly submerged.
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Bake covered
Dot the top with the 2 tablespoons butter. Cover the dish tightly with foil and bake until a knife slides into the center with almost no resistance, 45 to 55 minutes.
About 45 min. Cook mode has a timer for this step.
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Uncover and brown
Remove the foil and sprinkle the Parmesan over the top. Bake until the top is deep golden and the cream is bubbling thickly at the edges, 25 to 30 minutes more.
If the top browns well before the potatoes are tender, tent it loosely with foil again.
About 25 min. Cook mode has a timer for this step.
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Rest before serving
Let the gratin rest on a rack for 15 minutes. The cream thickens as it cools slightly, and the squares will hold their shape when you cut them.
About 15 min. Cook mode has a timer for this step.
Good to know
things I learned the hard way, so you can skip that part
- A mandoline gives the most even slices, but a sharp knife and patience work. Thicker slices need 10 to 15 more minutes covered.
- Yukon Gold potatoes give a creamier, less fluffy result and hold their shape well. Use them if you prefer that to russets.
- Make it ahead by baking fully, cooling, and refrigerating. Reheat covered at 350°F for 30 to 35 minutes, then uncover for the last 10.
- For a version with a thicker, softer sauce and no browned top, see creamy garlic scalloped potatoes.
- Storage. Refrigerate covered for up to 4 days. Reheat covered at 350°F until hot in the center, 25 to 35 minutes. Freezing isn't recommended, since the cream can separate.
Questions, answered
the questions my cousins text me
What's the difference between au gratin and scalloped potatoes?
Au gratin potatoes have cheese and a browned top, which is what "gratin" means. Scalloped potatoes are baked in a creamy sauce and traditionally have no cheese. If you want the creamy-sauce version, try creamy garlic scalloped potatoes.
Can I make au gratin potatoes ahead of time?
Yes. Bake it completely, cool it, cover and refrigerate for up to 2 days. Reheat covered at 350°F for 30 to 35 minutes, then uncover for the last 10 minutes to re-crisp the top.
Why are my au gratin potatoes still hard?
The slices were too thick or the dish was uncovered too soon. Keep the foil on until a knife slides in easily, then uncover to brown. Check your oven temperature, too; many run cool.
Why did my sauce turn greasy or curdle?
The cream got too hot or too little liquid covered the potatoes. Heat it only until steaming, pour it over evenly, and use full-fat cream. Milk alone tends to curdle in a long bake.
Can I use a different cheese?
Sharp white cheddar, Swiss, fontina or Comté all melt well. Grate your own, since bagged cheese has anti-caking starch that makes the sauce grainier.
Do I have to peel the potatoes?
No. Scrubbed russet or Yukon skins are fine and add a little texture. Peeling gives the smoothest, most uniform layers.
From the table
Made it? I want the full report: first bite, best compliment, and who tried to take the leftovers home.
Made it?
be honest. I can take it. probably.
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Published October 29, 2026.