Au Gratin Potatoes

No ratings yet

Au Gratin Potatoes start with thin slices of golden potatoes, layered in a rich, creamy, and ultra-cheesy sauce. This savory side dish is a comfort food guaranteed to be a crowd-pleaser!

Prep Time50

Cook Time1 30

Total Time2 20

Course: Appetizer, Side Dish

Cuisine: American, Vegetarian

Keyword: au gratin potatoes, au gratin potatoes recipe, potatoes au gratin

Servings: servings, as a side

Author: Chelsea Lords

Cost: $8.25

Equipment

Mandoline slicer
Potato peeler
9 x 9-inch baking pan
Large pot nonstick

Ingredients

Cooking spray
6 packed cups gold potatoes 2 pounds, see note 1
3 tablespoons unsalted butter
2 teaspoons minced garlic 2 cloves
3 tablespoons flour
Salt and pepper
2 cups milk see note 2
1 cup shredded sharp Cheddar cheese 3 ounces
1 cup shredded Gruyère cheese or more Cheddar, 3 ounces, divided
1/2 cup freshly grated Parmesan cheese see note 3
2 teaspoons fresh thyme or 1/4 teaspoon dried, optional

US - Metric

Instructions

Preheat oven to 350°F. Grease a 9x9-inch (or 2-quart) baking pan with cooking spray and set aside.
Peel and thinly slice potatoes (1/8-inch thick). I use a mandolin slicer for speed and accuracy (see note 1). Measure 6 tightly packed cups of sliced potatoes.
In a large nonstick pot, melt butter over low heat. Add garlic and sauté for 1 minute until fragrant. Stir in flour and whisk constantly for 1 minute until smooth (avoid browning). Gradually whisk in 1 cup of milk until smooth. Increase heat to medium-high and gradually add the second cup of milk. Stir occasionally until the mixture boils. Season with salt and pepper (I use 1 teaspoon salt and 1/4 teaspoon pepper).
Once boiling, reduce heat to medium-low and stir constantly for 2 minutes until the sauce thickens (see note 4). Remove from heat and let cool for 2 minutes. Stir in Cheddar cheese, a handful at a time, until melted and smooth. Add the sliced potatoes and stir to coat.
Assemble the dish by layering 1/3 of the potatoes in the prepared pan, then sprinkle in 1/2 cup Gruyere cheese and 1/3 of the fresh thyme. In the same pan, repeat with another 1/3 of the potatoes, the remaining 1/2 cup Gruyere, and 1/3 thyme. Finish with the remaining potatoes and thyme.
Cover the pan with foil and bake for 1 hour 15 minutes. Remove the foil and check for tenderness by piercing the potatoes with a knife. If not tender, bake a few more minutes and check again. Once tender, sprinkle 1/2 cup Parmesan cheese on top.
Bake uncovered for another 10–15 minutes or until golden and bubbly. For extra color, broil for 1 minute at the end. Let stand for 5–10 minutes before serving to allow the sauce to thicken.

Video

Notes

Note 1: Yukon gold potatoes are my favorite, but russet potatoes also work. Peel potatoes, rinse in cool water, then use a mandoline slicer set at 1/8th-inch thickness to cut potatoes.

Note 2: Whole milk works best for the richest result. 2% or 1% milk work, but avoid skim or plant-based milk alternatives.

Note 3: Grab a block of Parmesan cheese and grate on the small holes of a grater. Alternatively, use finely grated Parmesan cheese. Do not use shelf-stable Parmesan.

Note 4: The sauce should coat the back of a wooden spoon. If you can trace a clear line across the back of the spoon with your fingertip, and it stays, the sauce is thick enough.

Nutrition