How To Make the Best Au Gratin Potatoes
Au Gratin potatoes is possibly the great casserole ever: tender, fluffy potatoes bathed in a rich and creamy cheese sauce, then baked in a hot oven until bubbly and crisp.
Serves8 to 10
Prep15 minutes
Cook1 hour to 1 hour 15 minutes
Au gratin potatoes are one of the greatest casseroles of all time. Tender, fluffy potatoes are bathed in a rich and creamy cheese sauce, then baked in a hot oven until bubbly and crisp.
I’d dare to say au gratin potatoes are better than even the best mashed potatoes — and they’re easier, too.
If you thought au gratin potatoes required some special technique or hours over the stove, let me walk you through the easy step-by-step process for building this cheesy casserole, which is as welcome on the holiday table as it is any night of the week.
What Are Au Gratin Potatoes?
Au gratin is defined as a dish prepared with cheese, butter, and cooked in the oven or broiler, so any ingredient cooked with this method is au gratin.
Au gratin potatoes are a casserole of thinly sliced potatoes (and often garlic and onions) cooked in a sauce of cheese until tender.
The terms scalloped potatoes and au gratin potatoes are often used interchangeably, but technically the difference between the two lies in the fact that scalloped potatoes should not have cheese.
Scalloped potatoes are also cut thicker and stacked higher than au gratin potatoes. Luckily, creating very thin slices of potatoes for au gratin potatoes is easy with the help of a mandoline.
Tips for the Best Au Gratin Potatoes
- Use the right potatoes, and slice them very thin. For potatoes au gratin, you want a potato that will hold its shape when baked, but still bake up tender. Yukon gold or red potatoes work well because they have a thin skin that doesn’t require peeling.
- A sharp knife or mandoline is best for slicing. I prefer to use a mandoline to thinly slice the potatoes, but a sharp knife works too. As you slice the potatoes, do your best to keep them stacked, as this will make assembly faster.
- Grab a flavorful cheese (or a mixture of them). Cheese is the most important factor in au gratin potatoes, so be sure to pick something with pronounced flavor like Gruyère or sharp cheddar.
- Layer the potatoes and cheese sauce for more even baking. We’re turning most of our au gratin’s cheese into a cheese sauce, which helps distribute the cheese (and creamy butter and milk) throughout the dish.
- Start with a little sauce. Add some of this cheese sauce to the casserole dish before adding the potatoes and onions and then pour the rest of the cheese sauce over the potatoes and top with more cheese.
- Au gratin potatoes bake uncovered for 60 to 75 minutes. You’ll know they’re done when a paring knife can be easily slipped into the center of the casserole and the top is browned and crisped. Cool the whole dish for at least 10 minutes before scooping and serving.
Make-Ahead Tips for Au Gratin Potatoes
Au gratin potatoes can be made ahead of time and you have a few different options for how to approach this:
- Slice the potatoes the night before. Keep them in a bowl of cold water and store them covered in the refrigerator to prevent them from oxidizing and changing color.
- Assemble the casserole up to 2 days before you intend to serve it. Store it unbaked and covered in the refrigerator. Then bake according to the recipe instructions straight from the fridge when you need it.
- Assemble and bake the casserole. Cover and put it in the fridge then reheat for 30 minutes at 350°F.
What to Serve with Au Gratin Potatoes
In my world au gratin potatoes are a complete meal, but if you’d like to enjoy it as a side for weeknight dinner or a holiday spread try it with any of these delicious recipes below.
Au Gratin Potatoes
Au Gratin potatoes is possibly the great casserole ever: tender, fluffy potatoes bathed in a rich and creamy cheese sauce, then baked in a hot oven until bubbly and crisp.
Prep time 15 minutes
Cook time 1 hour to 1 hour 15 minutes
Serves 8 to 10
Nutritional Info
Ingredients
- 8 ounces
Gruyère or sharp cheddar cheese, or a combination
- 3 pounds
Yukon gold or red potatoes
- 1
small yellow onion
- 2 cloves
garlic
- 4 tablespoons
plus 1 teaspoon unsalted butter, divided
- 1/4 cup
all-purpose flour
- 1 teaspoon
Dijon mustard
- 1 teaspoon
kosher salt
- 1/4 teaspoon
freshly ground black pepper
- 2 cups
whole milk
Equipment
9x13-inch baking dish
Mandoline or sharp chef’s knife
Box grater
Measuring cups and spoons
4-quart pot
Whisk
Instructions
Heat the oven to 400ºF. Arrange a rack in the middle of the oven and heat the oven to 400ºF. Coat a 9x13-inch baking dish with 1 teaspoon of the unsalted butter.
Grate the cheese. Grate 8 ounces Gruyère or sharp cheddar cheese on the large hole of a box grater and set aside.
Thinly slice the potatoes and onions, and mince the garlic. Use a mandoline or a sharp chef’s to thinly slice 3 pounds Yukon gold or red potatoes into thin slices (no need to peel), doing your best to keep the potatoes slices stacked, as this will make assembly faster. Halve and thinly slice 1 small yellow onion. Finely chop 2 garlic cloves.
Make the cheese sauce. Place the remaining 4 tablespoons butter and the garlic in a large saucepan over medium heat. Once the butter is melted, add 1/4 cup all-purpose flour, 1 teaspoon kosher salt, 1 teaspoon Dijon mustard, and 1/2 teaspoon black pepper. Whisk to combine and cook until fragrant, about 1 minute. Add 2 cups whole milk and whisk vigorously until well-combined. Bring the mixture to a simmer, whisking occasionally. Remove from the heat, add the cheese, and whisk until mostly melted and smooth.
Layer the au gratin ingredients in the baking dish. Sprinkle the baking dish with about 2/3 of the sliced onions, arranging them in a single layer. Pour about 1 cup of the cheese sauce over the onions. Arrange the potatoes over the onions and cheese sauce — if you’ve kept them stacked, it is easy to fan them out into rows with the potatoes at an angle. Sprinkle the remaining onions over the potatoes, tucking them between rows if desired. Pour the remaining cheese sauce over the potatoes and spread into an even layer. Gently tap the baking dish against the counter to settle the sauce.
Bake for 60 to 75 minutes. Bake uncovered until the top and edges are browned and crisp, and a knife inserted in the middle can easily slide through the potatoes, 60 to 75 minutes.
Cool the gratin for 10 minutes before serving. Let the gratin cool for 10 minutes before scooping or slicing.
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