This Potatoes au Gratin recipe has layers of tender potatoes and onions, baked in a creamy and cheesy sauce until bubbly, crisp, and golden.
Looking for more potato side dishes? Try my Crispy Baked Potatoes next!
About This Recipe
Also known as scalloped potatoes. This is one of my FAVORITE side dishes for special occasions because it looks impressive, but is super easy to put together. All you do is make a cheese sauce, pour it over sliced potatoes and onions, then bake. The table is always filled with "oohs" and "ahhs" when it comes out.
I like to arrange the potatoes in a spiral in a circular pie dish to give it a really cool presentation. But you can layer the potatoes however you want, and use whatever-shaped baking dish you want. I recommend at least a 9x9-inch size baking dish, with 9x13-inch being the most ideal, to ensure the cheese sauce doesn't bubble over.
Key Ingredients
Potatoes: I recommend Russet potatoes or Yukon Gold Potatoes because they have a very tender texture when baked.
Onion: For savory depth. Avoid red onions because they will bleed color into the potatoes.
Butter: For making the cheese sauce. You can also use oil, but make sure not to reduce the amount since we need the same amount of oil as flour to prevent clumping.
Milk: The base of the cheese sauce. I recommend whole milk for the richest flavor.
Salt and pepper: About ½ a teaspoon of each, but you can add more or less to your own taste.
Cheddar cheese: For all that cheesy goodness! You can substitute the cheddar with gruyere or even replace some of it with Velveeta.
Instructions
STEP 1: Slice the potatoes thinly. I did about ¼ of an inch thick.
STEP 2: Layer ½ of the potatoes in the bottom of the casserole dish, followed by the onions and the remaining potatoes. Set aside.
STEP 3: Melt the butter in a large skillet over medium heat. Add the flour and cook for 1-2 minutes until golden. While whisking constantly, add the milk, salt, and black pepper. Cook until the mixture boils, then cook for 1 minute.
STEP 4: Stir in the cheddar cheese.
STEP 5: Pour the cheese sauce over the potatoes and onions.
STEP 6: Cover with foil and bake for 50-60 minutes. Remove the foil and bake for another 15-20 minutes until golden on top.
Potatoes au Gratin
Ingredients
- 6 medium russet potatoes (thinly sliced)
- 1 medium onion (sliced)
- 3 tablespoons butter
- 3 tablespoons all-purpose flour
- 2 cups milk
- ½ teaspoon salt
- ½ teaspoon black pepper (to taste)
- 1 ½ cups shredded Cheddar cheese
Instructions
- Preheat your oven to 400℉ and grease a 9x13-inch baking dish.
- Layer ½ of the potatoes in the bottom of the casserole dish, followed by the onions and the remaining potatoes. Set aside.
- Melt the butter in a large skillet over medium heat. Add the flour and cook for 1-2 minutes until golden.
- While whisking constantly, add the milk, salt, and black pepper. Cook until the mixture boils, then cook for 1 minute. Remove from the heat and stir in the cheddar cheese.
- Pour the cheese sauce over the potatoes and onions. Cover with foil and bake for 50-60 minutes. Remove the foil and bake for another 15-20 minutes until golden on top.
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