Potatoes au gratin is a classic side dish that goes with just about any holiday feast: Thanksgiving or Christmas turkey, Easter ham… you name it.
These potatoes are so decadent and comforting. I usually make a double batch of them for holiday celebrations and they disappear like magic in the blink of an eye.
HOW TO KEEP FRESHLY CUT POTATOES FROM BROWNING
Freshly cut potatoes turn brown because of a process called oxidation. Though they are completely safe to eat, they don’t look very appealing and can even color your sauce! To prevent this from happening, you just have to submerge them in cold water until you are ready to use them.
I would try not to keep them submerged in water for too long, however, or they may absorb a lot of excess liquid. Additionally, I also pat the potatoes dry with a clean kitchen towel before using them. This helps keep the sauce smooth and creamy (and not watery)!
THE BEST CHEESE TO USE FOR POTATOES AU GRATIN / SCALLOPED POTATOES
I find that the best combination of cheeses to use is equal parts Gruyère and cheddar. For the cheddar, I typically use an extra old (white) cheddar, a sharp (orange) cheddar, or a combination of the two, depending on what I have on hand.
Of course, feel free to substitute for whatever cheeses you prefer or whatever you have in the fridge already. Just be sure to account for the saltiness of different cheeses. Additionally, I wouldn’t use low fat cheeses, as the fat content helps keep the sauce rich and creamy and prevents it from breaking or separating in the oven.
CAN YOU MAKE SCALLOPED POTATOES AHEAD OF TIME?
Of course! (I know planning a holiday menu can be a lot of work, and everyone wants to lighten the load for the day of!)
You can just as easily prepare and assemble the potatoes, sprinkle them with cheese, and cover the baking dish in the fridge the night before. Just be sure to add a few extra minutes to your baking time to account for everything being chilled.
FOR HOW LONG SHOULD YOU BAKE SCALLOPED POTATOES?
A lot of recipes I’ve seen online only require you cook the potatoes for about an hour. You may very well be able to cook them for that long if you use a mandoline or any other fancy (and hard-to-clean) device that gets your potatoes super thin.
Otherwise, if you are cutting your potatoes by hand, they naturally tend to be a bit thicker and will likely require a bit more time in the oven. I have found 80 minutes covered — and then 30 to 40 minutes uncovered — is perfect and results in a soft, tender potato.
Start by preheating the oven to 350℉.
Peel, rinse, and slice 2 pounds of potatoes into ⅛” rounds. Place the sliced potatoes in a large bowl of cold water to prevent them from browning.
Then, in a pot or dutch oven, heat the butter and olive oil over medium heat until the butter stops foaming.
Add in the sliced onions and cook, stirring occasionally, for 10 minutes, until the onions are softened and translucent.
Add in the minced garlic and cook for about 60 seconds, until fragrant.
Next, stir in the flour and cook for an additional 2 minutes.
Meanwhile, heat the milk in a saucepan (or in the microwave) until scalding (hot, but not boiling). Set aside.
While whisking, slowly pour the hot milk into the pot and stir to combine, making sure there are no lumps. Turn up the heat slightly and continue to cook, stirring constantly, until the sauce thickens and just begins to bubble. Be careful not to scald the sauce on the bottom of the pot!
Turn off the heat, and stir in 1 cup of each shredded cheese, along with the salt and pepper. Taste for seasonings. Return to low heat to keep the sauce warm.
Then, in a buttered 9” by 13” oven-safe baking dish, place ⅓ of the potatoes on the bottom of the dish and cover with ⅓ of the cheese sauce. Continue to layer the potatoes and cheese sauce, ⅓ at a time.
Sprinkle the remaining ½ cup of each shredded cheese on the top of the potatoes.
Cover the dish with aluminum foil and bake in the center of the oven for 80 minutes.
Remove the foil and cook, uncovered, for another 30 to 40 minutes, until the potatoes are soft and the cheese is browned and bubbly.
Allow to cool for 10 minutes and serve hot.
Potatoes au Gratin (Cheesy Scalloped Potatoes)
These potatoes are rich, creamy, and incredibly cheesy! The ultimate comfort food, they are the perfect side to any holiday celebration.
- 2 pounds russet potatoes, washed, peeled, and ⅛" sliced (about 4 to 5 large potatoes)
- 1 medium yellow onion, peeled and ⅛" sliced
- 2 cloves of garlic, peeled and minced
- 2 Tbsp unsalted butter (plus more for greasing dish)
- 1 Tbsp extra virgin olive oil
- 3 Tbsp all-purpose flour
- 2 cups whole milk (or half-and-half)
- 1 cup Gruyère cheese, shredded
- 1 cup sharp white cheddar cheese, shredded
- 1 ¼ tsp kosher salt
- ½ tsp ground black pepper
For the Topping
- ½ cup Gruyère cheese, shredded
- ½ cup sharp white cheddar cheese, shredded
- Preheat oven to 350℉.
- Peel, rinse, and slice potatoes. To prevent them from browning, place sliced potatoes in a large bowl of cold water.2 pounds russet potatoes, washed, peeled, and ⅛" sliced
- In a pot or Dutch oven, heat butter and olive oil over medium heat until foaming subsides.2 Tbsp unsalted butter1 Tbsp extra virgin olive oil
- Add in sliced onions. Cook, stirring occasionally, until onions are softened and translucent (about 10 minutes).1 medium yellow onion, peeled and ⅛" sliced
- Add in minced garlic. Cook until fragrant (about 60 seconds).2 cloves of garlic, peeled and minced
- Stir in flour and cook for 2 minutes.3 Tbsp all-purpose flour
- Meanwhile, in a saucepan, heat milk until it is scalding (i.e. just before boiling). Keep on low heat.2 cups whole milk (or half-and-half)
- While whisking, slowly add the hot milk to the pot and cook until sauce is thick and creamy (about 5 minutes).
- Off heat, add in 1 cup of each shredded cheese, salt, and pepper. Stir, and keep warm on low heat. Taste for seasonings.1 cup Gruyère cheese, shredded1 cup sharp white cheddar cheese, shredded1 ¼ tsp kosher salt½ tsp ground black pepper
- Drain and dry off sliced potatoes. In a buttered 9" by 13" oven-safe baking dish, layer sliced potatoes with cheese sauce, ⅓ at a time.
- Sprinkle the remaining ½ cup of each shredded cheese on the top of the potatoes. Cover with aluminum foil and bake in the center of the oven for 80 minutes.½ cup Gruyère cheese, shredded½ cup sharp white cheddar cheese, shredded
- Remove foil and cook, uncovered, until the potatoes are soft and the top is browned and bubbly (about 30 to 40 minutes more).
- Allow to cool for 10 minutes. Serve hot.
- Preventing the potatoes from browning: Submerge the freshly sliced potatoes in a bowl of cold water to keep them fresh until you are ready to use them. Dry them off with a clean kitchen towel (before adding them to your baking dish) so that you don’t add too much extra moisture to your sauce.
- Make it ahead: You can prepare and assemble the dish the night before and place it in the refrigerator, covered with plastic wrap, until the next day. Just be sure to allow a few extra minutes of baking time to account for the chilled ingredients.
- Baking time: Baking time largely depends on the type of potatoes you use and how thick they are cut. If you use a mandoline (or any other kitchen device that slices potatoes very thin), they will likely require less time in the oven. However, cutting them by hand typically results in thicker slices, which will require a bit more time in the oven to become soft and tender.