Cheesy Au Gratin Potatoes
Au gratin potatoes baked in a from-scratch cheddar and Gruyere cream sauce until golden and bubbling. The classic cheesy potato side, done right.
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Au gratin potatoes are the dish that disappears first at every holiday table in my family, and honestly at every Sunday dinner too. Thin slices of potato bake in a cheddar and Gruyere cream sauce until the edges bubble up brown and the top goes crackly and golden. Underneath, the potatoes turn soft enough to cut with the side of a fork.
The part that makes or breaks this dish is building a real roux first. Butter and flour cooked together for a minute, then whisked with milk and cream, gives you a sauce that stays thick and glossy through a long bake. Dump plain cream over raw potatoes and the heat can pull it apart into something watery with a greasy film on top. The flour holds it together.
How thin you slice matters just as much. I go 1/8 inch, about as thin as a coin, and a mandoline gets it done in five minutes instead of fifteen. Even slices cook at the same rate and layer up tight, so you get creamy potato all the way down instead of a few hard pieces hiding in the middle.
Why You’ll Love This Au Gratin Potatoes Recipe
- It’s genuinely cheesy. Three full cups of sharp cheddar and Gruyere go in, half melted into the sauce and half browned on top.
- A sauce that never breaks. The butter-and-flour roux keeps the cream sauce smooth and thick through a 70-minute bake.
- Make it ahead. You can assemble the whole dish a day early and slide it into the oven when the rest of dinner is going.
- It stretches five pounds of dinner. Potatoes, milk, and a block of cheese feed a crowd for a few dollars a head.
Au Gratin Potatoes Ingredients
Shred your own cheese off the block. Bagged shreds are coated with starch to keep them from clumping in the package, and that coating is what turns a smooth cheese sauce grainy. Sharp cheddar brings the flavor, Gruyere brings the stretch and the nutty note.
- 3 lbs Yukon Gold potatoes, peeled and sliced 1/8 inch thick
- 4 tbsp butter, plus more for the dish
- 1 small yellow onion, finely diced
- 3 cloves garlic, minced
- 4 tbsp all-purpose flour
- 2 cups whole milk
- 1 cup heavy cream
- 1 1/2 tsp salt
- 1/2 tsp black pepper
- 1/4 tsp ground nutmeg
- 2 cups shredded sharp cheddar, divided
- 1 cup shredded Gruyere, divided
- 2 tbsp fresh chives, chopped, for garnish
Recipe Variations
- Layer in 2 cups of diced ham with the potatoes to turn this side dish into a full dinner, which is a good way to use up a holiday ham.
- Swap the Gruyere for Swiss or Monterey Jack if that’s what your store carries. Both melt smoothly and keep the sauce mild for kids.
- Stir 4 slices of crumbled cooked bacon into the sauce before layering for a smokier, saltier version.
How to Make Au Gratin Potatoes
- Heat the oven and prep the dish: Heat the oven to 375°F and butter a 9×13-inch baking dish. Peel the potatoes and slice them 1/8 inch thick, using a mandoline if you have one. Keep the slices in a bowl of cold water if you’re working slowly so they don’t brown.
- Start the sauce: Melt the 4 tablespoons butter in a large saucepan over medium heat. Add the onion and cook for 3-4 minutes until soft and translucent, then stir in the garlic and cook for 30 seconds until fragrant.
- Cook the roux: Sprinkle the flour over the butter and onion and stir constantly for 1 full minute. The mixture will look like wet sand and smell slightly toasty. That minute cooks out the raw flour taste.
- Whisk in the milk and cream: Slowly pour in the milk and heavy cream, whisking the whole time so no lumps form. Add the salt, pepper, and nutmeg. Bring to a gentle simmer and cook for 3-4 minutes, whisking often, until the sauce thickens enough to coat the back of a spoon.
- Melt in the cheese: Pull the pan off the heat and stir in 1 1/2 cups of the cheddar and 1/2 cup of the Gruyere until completely melted and smooth. Taking it off the burner first keeps the cheese from getting stringy or grainy.
- Layer the au gratin potatoes: Drain and pat the potato slices dry. Shingle half of them across the bottom of the baking dish, overlapping the edges. Pour half the cheese sauce over the top and spread it to the corners. Repeat with the remaining potatoes and sauce, then scatter the last 1/2 cup cheddar and 1/2 cup Gruyere over the top.
- Bake covered, then uncovered: Cover the dish tightly with foil and bake at 375°F for 40 minutes. Remove the foil and bake for another 30 minutes, until the top is deep golden and bubbling and a paring knife slides through the center with no resistance.
- Rest and serve: Let the dish sit for 10 minutes before serving so the sauce sets up instead of running across the plate. Sprinkle with chopped chives right before it goes to the table.
Recipe FAQs
What’s the Difference Between Au Gratin Potatoes and Scalloped Potatoes?
Cheese. Au gratin potatoes are baked in a cheese sauce with more cheese browned on top, which is where the crusty golden surface comes from. Traditional scalloped potatoes are cream or milk only, seasoned simply, with no cheese at all. Plenty of American recipes now add a little cheese to scalloped potatoes too, so the line has blurred at the grocery store, but the classic distinction holds: gratin means cheese and a browned top.
What Potatoes Work Best?
Yukon Golds are my first pick. They have moderate starch, so they hold their shape and soak up sauce without falling apart. Russets work too and give you a softer, fluffier result, but they can turn mushy if you slice them thick. Skip waxy red potatoes; they stay firm and never get that melting texture.
Why Is My Sauce Watery or Curdled?
Usually one of two things. Either the roux was skipped or shorted, so nothing was holding the dairy together, or the cheese went in over direct heat and separated. Cook the flour a full minute, and take the pan off the burner before the cheese goes in.
Can I Make Au Gratin Potatoes Ahead of Time?
Yes. Assemble the whole dish, cover it, and refrigerate up to 24 hours. Pull it out 30 minutes before baking and add about 10 minutes to the covered bake time since it’s starting cold.
Do I Have to Peel the Potatoes?
Not if you don’t want to. Yukon Gold skins are thin and cook up tender, so scrub them well and slice as usual. I peel when it’s going on a holiday table and leave the skins on for a Tuesday.
Cooking Tips
- Pat the potato slices dry before layering. Wet slices dilute the sauce and add water to the bottom of the dish as they bake.
- Shingle the slices at an angle instead of dropping them in loose. Overlapping layers pack tighter and give you clean, sliceable squares instead of a pile.
- If the top browns faster than the potatoes cook, lay the foil back on for the last stretch. The knife test through the center is what tells you it’s done, not the color on top.
Storage and Freezing
To store: Cover and refrigerate leftovers for up to 4 days. The sauce firms up cold, which is normal.
To freeze: Freezing isn’t great here. The cream sauce separates as it thaws and the potatoes go grainy and mealy. If you want a head start, assemble it fresh and refrigerate up to a day instead.
To reheat: Cover with foil and warm in a 325°F oven for 20-25 minutes, or microwave single portions in 1-minute bursts. A splash of milk stirred into individual servings loosens the sauce back up.
How to Serve Au Gratin Potatoes
Au Gratin Potatoes belong next to something roasted. Baked ham, a roast chicken, or a simple pan-seared pork chop all work, and a pile of green beans or a crisp salad cuts through the richness. If you want the same comfort without the cheese, our Scalloped Potatoes recipe is the cream-only version of this same idea.
Loved This Recipe?
Au Gratin Potatoes are worth the hour and a half, and the empty dish at the end of dinner makes that case better than I can.
Leave a star rating in the comments below, it helps other people find this recipe. Made it? Tag @allwellfed on Instagram, I love seeing this one in other people’s kitchens.
Cheesy Au Gratin Potatoes
Equipment
Ingredients
- 3 lbs Yukon Gold potatoes peeled and sliced 1/8 inch thick
- 4 tbsp butter plus more for the dish
- 1 small yellow onion finely diced
- 3 cloves garlic minced
- 4 tbsp all-purpose flour
- 2 cups whole milk
- 1 cup heavy cream
- 1 1/2 tsp salt
- 1/2 tsp black pepper
- 1/4 tsp ground nutmeg
- 2 cups shredded sharp cheddar divided
- 1 cup shredded Gruyere divided
- 2 tbsp fresh chives chopped, for garnish
Instructions
- Heat the oven and prep the dish: Heat the oven to 375°F and butter a 9×13-inch baking dish. Peel the potatoes and slice them 1/8 inch thick, using a mandoline if you have one. Keep the slices in a bowl of cold water if you’re working slowly so they don’t brown.
- Start the sauce: Melt the 4 tablespoons butter in a large saucepan over medium heat. Add the onion and cook for 3-4 minutes until soft and translucent, then stir in the garlic and cook for 30 seconds until fragrant.
- Cook the roux: Sprinkle the flour over the butter and onion and stir constantly for 1 full minute. The mixture will look like wet sand and smell slightly toasty. That minute cooks out the raw flour taste.
- Whisk in the milk and cream: Slowly pour in the milk and heavy cream, whisking the whole time so no lumps form. Add the salt, pepper, and nutmeg. Bring to a gentle simmer and cook for 3-4 minutes, whisking often, until the sauce thickens enough to coat the back of a spoon.
- Melt in the cheese: Pull the pan off the heat and stir in 1 1/2 cups of the cheddar and 1/2 cup of the Gruyere until completely melted and smooth. Taking it off the burner first keeps the cheese from getting stringy or grainy.
- Layer the au gratin potatoes: Drain and pat the potato slices dry. Shingle half of them across the bottom of the baking dish, overlapping the edges. Pour half the cheese sauce over the top and spread it to the corners. Repeat with the remaining potatoes and sauce, then scatter the last 1/2 cup cheddar and 1/2 cup Gruyere over the top.
- Bake covered, then uncovered: Cover the dish tightly with foil and bake at 375°F for 40 minutes. Remove the foil and bake for another 30 minutes, until the top is deep golden and bubbling and a paring knife slides through the center with no resistance.
- Rest and serve: Let the dish sit for 10 minutes before serving so the sauce sets up instead of running across the plate. Sprinkle with chopped chives right before it goes to the table.
Notes
If you made this, leave a star rating down in the comments. It takes about ten seconds, and it’s how other cooks decide whether a recipe is worth trying.
