This au gratin potatoes recipe belongs on your holiday table! A delicious, decadent side dish, it features thinly sliced potatoes, onion, and cheese baked in a rich, garlicky cream sauce.
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This first time I made this au gratin potatoes recipe, Jack and I polished off half the pan ourselves. The thinly sliced potatoes are baked in a rich, garlicky cream sauce with onion and plenty of cheese (cheddar, Gruyère, AND Parmesan for a tangy, nutty punch).
I developed the recipe with the holidays in mind. These creamy au gratin potatoes would be an absolutely perfect side dish for Thanksgiving or Christmas. They taste decadent and flavorful, yet they’re simple to put together (and you can even make them ahead). If you’re looking for a show-stopping recipe for your table this year, you’re going to love these!
Au Gratin Potatoes vs Scalloped Potatoes
If you’re thinking, Wait, how are these au gratin potatoes different from scalloped potatoes?, it’s a good question. The two dishes are both creamy potato casseroles, after all. Traditionally, the difference comes down to cheese. Au gratin potatoes always have cheese, whereas scalloped potatoes often don’t.
However, I do use cheese in my scalloped potatoes (a family tradition!), so other differences set my recipes apart. These au gratin potatoes feature a richer sauce made with heavy cream and no roux, plus a higher ratio of cheese to potato. I took some inspiration from the French dish potatoes dauphinoise in developing this recipe, using the cream and Gruyère cheese for delectably rich flavor. It’s a simple, yet elevated, side dish for a holiday meal.
Best Potatoes for Au Gratin
I think russet potatoes are best for potatoes au gratin. Their high starch content helps thicken the sauce, and as they absorb the cream in the oven, they become incredibly tender. I love that tender texture with the creamy sauce and cheese here. Slicing them thinly (I use a mandoline for this) helps them cook evenly and fully in the bake time.
How to Make Au Gratin Potatoes
One thing I love about this au gratin potatoes recipe is how easy it is to assemble. Once you thinly slice the potatoes and onions and grate the cheese, it has four main steps:
1. Whisk together the cream sauce. No cooking required! Just combine the cream, garlic, Dijon mustard, salt, and pepper in a bowl. Because of the cream’s fat content, it doesn’t need a roux to thicken it.
2. Layer up the gratin. Arrange a third of the potatoes in a greased 2-quart baking dish. Top with half the onions, a third of the cream mixture, and a third of the shredded cheddar and/or Gruyère cheese. Repeat these layers, then top with the remaining potatoes and cream. Cover with foil.
3. Bake, covered, at 400°F until the potatoes are tender. This initial bake will take 1 hour to 1 hour and 15 minutes.
4. Add the remaining cheese and broil to brown the top. The gratin is ready when the cream is bubbling and the potatoes are browned around the edges.
Tip:Â Before serving, let the potatoes stand at room temperature for 20 minutes. This will give the sauce time to set up slightly. (The potatoes are also blazing hot when they come out of the oven!)
How to Store and Reheat
I find that these potatoes are surprisingly good leftover. Store them in an airtight container in the refrigerator for up to 3 days. They’re slightly less creamy after sitting in the fridge, but the flavor is still fantastic. Reheat them in the microwave or in a covered dish in a 350°F oven.
I don’t recommend freezing them. The cheese and potatoes have a grainy texture when they thaw.
Can you make au gratin potatoes ahead of time?
Yes! You can prep these au gratin potatoes up to 1 day ahead. Fully assemble them and do the covered bake until the potatoes are tender. Don’t broil them at this point. Let cool to room temperature, then store in the fridge.
The next day, let stand at room temperature for 30 minutes, then bake, covered, in a 350°F oven for about 30 minutes, until heated through. Sprinkle with the remaining cheese and broil according to the recipe before serving.
More Potato Side Dishes to Try
If you love this gratin, try one of these delicious potato recipes next:
Au Gratin Potatoes
Ingredients
- Unsalted butter, for the pan
- 1¼ cups heavy cream
- 3 garlic cloves, grated
- ½ teaspoon Dijon mustard
- 1½ teaspoons sea salt
- Freshly ground black pepper
- 2 pounds russet potatoes, about 2 large or 3 small potatoes, thinly sliced on a mandoline â…›-inch thick
- ½ medium yellow onion, thinly sliced
- 2 cups shredded cheddar cheese and/or Gruyère cheese, I use a mix*
- â…“ cup freshly grated Parmesan cheese
- Chopped fresh parsley, for garnish
Instructions
- Preheat the oven to 400°F and grease a 2-quart baking dish with butter.
- In a medium bowl, whisk together the cream, garlic, mustard, salt, and several grinds of pepper.
- Layer a third of the potatoes in the prepared baking dish. Top with half the sliced onions, a third of the cream mixture, and a third of the cheddar and/or Gruyère cheese. Repeat with another third of the potatoes, the remaining onions, another third of the cream mixture, and another third of the cheese. Top with the remaining potatoes and drizzle with the remaining cream. (Stick the remaining cheddar and Gruyère in the fridge for now.)
- Cover and bake for 1 hour to 1 hour and 15 minutes, or until the potatoes are easily pierced with a paring knife. Remove from the oven and turn on the broiler.
- Uncover the potatoes and top with the remaining cheddar and Gruyère and the Parmesan cheese. Broil for 8 to 15 minutes, or until the cream is bubbling and the potatoes are nicely browned. Remove from the oven and let stand for 20 minutes.
- Garnish with parsley and serve.
