Au Gratin Potatoes

Baking dish of Potatoes Au Gratin with portion taken out.

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Potatoes Au Gratin are a classic potato dish that is easy to make at home and is sure to win over any crowd. Thinly sliced potatoes combine with a rich béchamel sauce to give you the best side dish.

Prep Time15

Cook Time1 30

Total Time1 45

Servings: servings

Calories: 325kcal

Author: Lisa Longley

Ingredients

3 tablespoons unsalted butter
1 small yellow onion diced
3 garlic cloves minced
1 teaspoon kosher salt or 1/2 teaspoon table salt
1/8 teaspoon black pepper
3 tablespoons all purpose flour
2 cups half and half
2 cups cheddar cheese shredded, divided, see note 1
3 medium russet potatoes about 2 pounds, sliced thin, see note 2
1/4 cup Parmesan cheese

Instructions

Preheat your oven to 350 degrees Fahrenheit. Spray a 2-quart casserole dish with cooking spray.
In a small saucepan over medium heat, melt the butter. Add in the onions, garlic, salt, and pepper. Sauté until the onions start to soften, about three minutes.
3 tablespoons unsalted butter, 1 small yellow onion, 1 teaspoon kosher salt, 1/8 teaspoon black pepper, 3 garlic cloves
Whisk in the flour until you no longer see any streaks of white. Then slowly whisk in the half and half, a few tablespoons at a time, adding more only once what you have just added has been absorbed. While you want to go slowly, this should only take about 1 minute. Bring to a simmer.
3 tablespoons all purpose flour, 2 cups half and half
Add 1 1/2 cups of the cheddar cheese, a few handfuls at a time, whisking to combine. Add more cheese once what you have just added is melted.
2 cups cheddar cheese
Layer half the potatoes in the bottom of the prepared pan. Top with half of the prepared cream sauce. Layer the second half of the potatoes. Top with the remaining cream sauce, then add the remaining 1/2 cup cheddar cheese and the Parmesan cheese.
2 cups cheddar cheese, 3 medium russet potatoes, 1/4 cup Parmesan cheese
Cover the casserole dish with foil and bake for 70 minutes. Remove the foil and continue baking for 20 minutes.

Notes

Do not use sharp cheddar as it is more likely to separate while baking.
The russet potatoes should be sliced to 1/8 inch (3 mm) thickness. This is best done with a mandoline slicer.

Nutrition