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5 from 3 votes

Au Gratin Potatoes Recipe

Rich and comforting, with the perfect combination of tender potatoes and a silky, flavorful sauce.
Prep Time30 mins
Cook Time1 hr 30 mins
Total Time2 hrs
Course: Vegetable
Servings: 8 - 10
Author: Tricia


  • Mandoline Slicer


  • 2 tablespoons unsalted butter
  • 2 tablespoons all-purpose flour
  • 1 teaspoon salt
  • ½ teaspoon ground black pepper
  • pinch of fresh grated nutmeg
  • pinch of cayenne pepper
  • ¼ teaspoon garlic powder
  • 2 ½ cups half-and-half
  • ½ cup shredded Gruyère cheese, plus 3 tablespoons for topping
  • 2 ½ to 3 pounds waxy potatoes (like Yukon gold)


  • Preheat oven to 350° F. Lightly grease a 9x9-inch baking dish, or 6 cup gratin dish with vegetable cooking spray or butter. Place the baking dish on a cookie sheet. Set aside.
  • In a medium saucepan melt 2 tablespoons butter over medium heat. Add the flour and cook, stirring constantly for 3 to 4 minutes. Add the salt, pepper, nutmeg, cayenne, garlic powder and half-and-half. Cook, stirring constantly, about 3 to 5 minutes or until it starts to thicken. Remove from the heat, cover to keep warm.
  • Peel and slice the potatoes to 1/16 to 1/8-inch thickness. Layer ⅓ of the potatoes in the prepared baking dish. Spoon ⅓ of the sauce over the potatoes. Sprinkle with ¼ cup of the cheese.
  • Repeat layering ½ of the remaining potatoes, ½ the remaining sauce and sprinkle with the remaining ¼ cup Gruyère.
  • Top with the remaining potatoes then pour all the remaining sauce over the top.
  • Bake, uncovered, for 60 minutes. * If the top is drying out too quickly, remove the casserole from the oven and gently press down with a large flat spatula submerging the potatoes in the sauce. Tent with foil, if needed, and continue baking.
  • After 1 hour of baking, sprinkle the potatoes with the remaining 3 tablespoons of cheese. Return the pan to the oven and cook another 30 minutes or until the potatoes are fork tender and the top is well browned.
  • Remove from the oven and allow the potatoes to rest 15 minutes before serving. Garnish with parsley, if desired.


* There is no need to press the potatoes down into the sauce if they are still covered.
Once assembled, this casserole can be refrigerated for up to 1 day before baking. Lightly coat a piece of plastic wrap with vegetable cooking spray and press it down on the top of the potato casserole to seal out the air. Wrap with foil and refrigerate until needed. Allow the dish to come to room temperature for 1 hour before baking.