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Square of baked au gratin potatoes on gray plate.

Cheesy Au Gratin Potatoes

Yield: 6 servings
Prep Time: 20 minutes
Cook Time: 1 hour 25 minutes
Total Time: 1 hour 45 minutes

Ingredients

  • 1 ¼ cups (about 5 ounces) freshly shredded sharp cheddar cheese
  • 1 ¼ cups (about 5 ounces) freshly shredded Monterey jack cheese
  • ½ cup (about 2 ounces) freshly grated Parmesan cheese
  • 2 teaspoons cornstarch
  • 3 pounds russet potatoes, peeled and sliced 1/8-inch thick (see note)
  • Salt and pepper
  • ¾ cup heavy cream
  • ½ cup low-sodium chicken broth

Instructions 

  • Preheat the oven to 350 degrees and adjust an oven rack to the middle position.
  • In a large bowl or ziploc bag, toss the cheeses and cornstarch together until evenly coated.
  • IMPORTANT: See note below for size of pan to use.
  • Layer half of the potatoes in the bottom of the pan overlapping slightly in a shingle-type pattern.
  • Sprinkle the potatoes evenly with 1 1/2 cups of the cheese mixture, 1/2 teaspoon salt, and 1/4 teaspoon pepper.
  • Top with the remaining potatoes, shingling them neatly and evenly over the cheese. Sprinkle another 1/2 teaspoon salt and 1/4 teaspoon pepper evenly over the top.
  • Combine the cream and broth in a large measuring cup and pour the mixture over the potatoes.
  • Sprinkle the remaining cheese mixture over the top and bake until golden brown and a fork inserted into the center slides in easily with little resistance, 75 to 85 minutes (check the potatoes after 60 minutes if baking in a 9X13-inch pan).
  • Let the potatoes cool for 10 minutes to set up. Serve warm.

Notes

Pan Size: The original recipe called for making these potatoes in a 2- or 3-quart gratin dish, which can range anywhere from 7 to 10 inches in length (and is often oval shaped). 
  • If you don't have a gratin dish, this recipe can be baked in a dish of an equivalent size (see following notes). 
  • A 9X13-inch dish is considered a 3-quart dish. If using this dish for these au gratin potatoes, the assembled layers will be thinner than if baking in a smaller dish, so the baking time will likely be shorter (check after about 60 minutes). The recipe can be increased by half (so 1 1/2 all the ingredients) and baked in a 9X13-inch pan for thicker layers.
  • Other pan sizes, like a 9X9-inch pan or a 10 1/2-X7 1/2-inch pan can be used for a thicker potato casserole.
Slicing the Potatoes: It is hard to get the potatoes thinly and evenly sliced by hand, but not impossible. A food processor fitted with a slicing disk set to 1/8-inch, as well as a mandoline, works great to slice the potatoes evenly.