Cheesy Au Gratin Potatoes

The first time I made au gratin potatoes, the top looked ready long before the potatoes underneath were tender. A golden, cheesy surface can be misleading when the slices are layered in a deep dish, so this version bakes covered first and uncovered at the end. That gives the potatoes time to soften before the cheddar gets its turn in the oven.

I use Yukon Gold potatoes and slice them thinly, then overlap them in the baking dish so each layer cooks evenly. The sauce starts with butter, garlic, and flour; whisking in the milk and cream gradually gives it a smooth, spoon-coating texture before the cheese goes in. Sharp cheddar brings plenty of flavor without needing a long list of extras.

After the covered bake, the foil comes off so the top can turn golden. Give the dish its full rest before serving, and you’ll have tender layers with creamy sauce tucked between them.

Why Even Potato Slices Matter More Than Extra Sauce

When the slices vary in thickness, the thin ones soften early while thicker pieces stay firm. That’s especially noticeable in a layered casserole: the sauce can look bubbling and finished even though a few potato slices in the middle need more time. Cutting the potatoes to the same thin thickness helps the whole dish cook at a similar pace.

Overlap the slices rather than stacking them in a loose pile. The layers should sit snugly across the dish, with the sauce poured over the top to work its way between them as the potatoes bake. Yukon Golds are a good fit because they turn tender while keeping enough structure to serve in layers. The knife test matters more than the color of the top; the potatoes are ready when a knife slides easily into them.

Don’t rush the covered portion of the bake to chase a browned top. The foil shields the surface while the potatoes soften, then uncovering the dish gives the cheddar time to brown. That order solves the common problem of a beautiful top over undercooked potatoes.

What the Potatoes, Cream, and Cheddar Each Bring

• Yukon Gold potatoes — Their creamy texture and moderate starchiness make tender layers that don’t immediately fall apart. Choose firm potatoes without soft spots; there’s no need to pay extra for specialty produce. Russet potatoes work as a substitute, though they’re starchier and tend to make the layers softer.
• Whole milk and heavy cream — Together, they make a rich sauce that still pours easily over the potato layers. Fresh dairy is important, but a premium brand isn’t necessary. If you don’t have heavy cream, use the same volume of half-and-half; the sauce will be less rich.
• Sharp cheddar — Its stronger, tangy taste stands up to the potatoes and cream. A block that you shred yourself melts smoothly, but any good-quality sharp cheddar works. Gruyère can replace the cheddar for a nuttier, less tangy result.
• Butter and flour — Butter carries the garlic through the sauce, while flour thickens the milk and cream into a coating sauce. All-purpose flour is dependable here; for a gluten-free version, use a cup-for-cup gluten-free flour blend in its place. The sauce texture may vary a little by blend.
• Garlic — Minced garlic gives the sauce a savory base without taking over the cheddar. Fresh cloves have the clearest flavor, and smaller cloves are easy to mince finely so they distribute through the sauce.

How to Layer, Sauce, and Bake the Potatoes

Build Two Even Layers

Heat the oven to 375°F and grease a 9×13-inch baking dish with butter. Arrange half of the peeled, thinly sliced potatoes in overlapping rows, then season them with half the salt and pepper. Add the remaining potatoes in another layer and season those too. Keeping the slices in an even layer helps avoid pockets that cook more slowly.

Cook the Garlic Flour Base

Melt the butter in a medium saucepan over medium heat, then add the minced garlic and cook it for 30 seconds. Whisk in the flour and cook for 1 minute, stirring so it combines with the butter instead of forming dry patches. Gradually whisk in the milk and heavy cream, then add the salt. If you pour the dairy in all at once, lumps are harder to whisk out.

Thicken Before Adding the Cheddar

Cook the sauce, stirring, for 4 to 6 minutes, until it bubbles and is thick enough to coat a spoon. It should still flow easily when you lift the spoon; a paste-thick sauce won’t spread as evenly over the potato layers. Take the saucepan off the heat before stirring in 1 1/2 cups of the cheddar. Stir until the cheese melts into the sauce.

Bake Covered, Then Brown the Top

Pour the cheese sauce evenly over the potatoes and sprinkle the remaining cheddar over the surface. Cover the dish tightly with foil and bake for 50 to 60 minutes, then uncover and bake for another 25 to 35 minutes. The top should be golden brown, and a knife should slide easily into the potatoes; if the knife meets resistance, keep baking until the potatoes are tender. Rest the finished dish for 15 minutes before serving.

Two Easy Changes for Different Tables

Questions That Come Up Before the First Scoop

Cheesy Au Gratin Potatoes

Cheesy au gratin potatoes layer thinly sliced Yukon Gold potatoes with a creamy sharp cheddar sauce. They bake under foil until tender, then uncover to develop a golden-brown top.

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Prep Time 20 minutes mins

Cook Time 1 hour hr 32 minutes mins

resting 15 minutes mins

Total Time 2 hours hrs 7 minutes mins

Servings: 8 servings

Course: Side Dish

Cuisine: American

Calories: 625

Ingredients Equipment Method Notes

Ingredients

  

For the potatoes

• 1 tbsp unsalted butter for greasing the baking dish
• 3 lb Yukon Gold potatoes peeled and sliced 1/8 inch thick
• 1 tsp kosher salt
• 0.5 tsp black pepper

For the cheese sauce

• 3 tbsp unsalted butter
• 2 cloves garlic minced
• 3 tbsp all-purpose flour
• 2 cups whole milk
• 1 cup heavy cream
• 0.25 tsp kosher salt
• 2 cups sharp cheddar cheese shredded, divided

Equipment

• 1 9x13-inch baking dish

Method

 

Prepare the potatoes

1. Preheat the oven to 375°F.
2. Grease a 9x13-inch baking dish with the 1 tablespoon butter.
3. Arrange half the potatoes in the dish, overlapping the slices.
4. Season with half the salt and pepper.
5. Repeat with the remaining potatoes and season with the remaining salt and pepper.

Make the cheese sauce

1. Melt the 3 tablespoons butter in a medium saucepan over medium heat, add the garlic, and cook for 30 seconds.
2. Whisk in the flour and cook for 1 minute.
3. Gradually whisk in the milk and heavy cream.
4. Whisk in the 1/4 teaspoon salt.
5. Cook, stirring, for 4 to 6 minutes until the sauce is bubbling and thick enough to coat a spoon.
6. Remove the saucepan from the heat and stir in 1 1/2 cups of the cheddar until melted.

Assemble and bake

1. Pour the cheese sauce evenly over the potatoes.
2. Sprinkle with the remaining 1/2 cup cheddar.
3. Cover the dish tightly with foil and bake for 50 to 60 minutes.
4. Uncover and bake for 25 to 35 minutes more, until a knife slides easily into the potatoes and the top is golden brown.
5. Let the potatoes rest for 15 minutes before serving.

Notes

Slice the potatoes evenly so they cook at the same rate. Refrigerate leftovers for up to 4 days; freezing is not recommended because the creamy sauce may separate. For a gluten-free option, substitute a cup-for-cup gluten-free flour blend.