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Classic Potato Au Gratin

Classic Potato Au Gratin
  • Yield: 12
A classic potato au gratin made with Idaho russets, local shallots, dairy and herbs


  • 4 pounds Idaho russet potatoes, scrubbed, very thinly sliced on a mandoline
  • 5 garlic cloves, divided (available at your local Farmers Market during season)
  • 1 tablespoon unsalted Idaho butter, room temperature
  • 2 medium Idaho shallots, quartered through root ends
  • 2½ cups heavy Idaho cream
  • 3 ounces Gruyère, finely grated
  • 1 ounce Parmesan, finely grated
  • 1 tablespoon kosher salt
  • 1 teaspoon freshly ground black pepper
  • 1 tablespoon Idaho grown thyme leaves, plus additional for garnish
  • Bake ahead: Gratin can be baked 1 day ahead. Cover and chill. Bring to room temperature before broiling.


  • Preheat oven to 325° F.

  • Cut 1 garlic clove in half and rub the inside of a 3-qt. shallow baking dish. Butter the inside of dish until evenly coated.

  • Bring shallots, cream, salt, pepper, 1 Tbsp thyme and remaining 4 garlic cloves to a simmer in a small saucepan over low heat. When simmering the cream, make sure it’s over gentle heat (if it over-reduces, it will break)

  • Cook until shallots and garlic are very soft, 15–20 minutes. Let cool slightly. Transfer to a blender and blend until smooth.

  • Arrange potato slices in prepared dish, tuck smaller slices into any gaps to fill. Pour cream mixture over potatoes and cover dish tightly with foil. Bake potatoes until tender and creamy, 60–75 minutes. Let cool.

  • Place rack in highest position; heat broiler. Remove foil and top potatoes with Gruyère and Parmesan.

  • Broil until cheese is bubbling and top of gratin is golden brown, 5–10 minutes. Serve topped with more thyme leaves.