Mixed Potato Gratin

Have fun with the arrangement when shingling the colorful potato slices.

Mixed Potato Gratin
 
Makes 8 to 10 servings
Ingredients
  • 1½ pounds medium Yukon Gold potatoes, peeled
  • 1½ pounds medium sweet potatoes, peeled and halved lengthwise
  • 1¾ cups heavy whipping cream
  • ⅓ cup minced garlic
  • ¼ cup unsalted butter, softened
  • 1 tablespoon chopped fresh sage
  • 2 teaspoons kosher salt
  • 2 teaspoons chopped fresh thyme
  • ½ teaspoon ground black pepper
  • ¼ teaspoon ground nutmeg
  • 1 cup shredded Gruyère cheese, divided
  • ½ cup shredded Parmesan cheese
  • Garnish: chopped fresh sage
Instructions
  1. Preheat oven to 400°. Butter an 11×8-inch baking dish; place on rimmed baking sheet. Fill a large bowl with cold water.
  2. Using a very sharp knife or a mandolin, slice potatoes crosswise into ⅛-inch-thick slices. Add potatoes slices to bowl with water as you work.
  3. Drain and thoroughly pat potatoes dry. Tightly shingle half of potatoes evenly in bottom of prepared baking dish in desired pattern.
  4. In a medium saucepan, combine cream, garlic, butter, sage, salt, thyme, pepper, and nutmeg; bring to a simmer over medium heat. Pour half of cream mixture over potatoes in baking dish; sprinkle with ½ cup Gruyère. Shingle remaining potatoes in desired pattern over cheese. Top with remaining cream mixture, and remaining ½ cup Gruyère. Top with Parmesan. Cover baking dish with foil, poking holes in top with a wooden pick.
  5. Bake for 40 minutes. Uncover and bake until potatoes are tender and gratin is golden brown and bubbly, 25 to 30 minutes, recovering with foil to prevent excess browning, if needed. Let stand for 40 minutes before serving. Garnish with sage, if desired.
Notes
KITCHEN TIP-We recommend wearing a cut-resistant glove when slicing hard vegetables on a mandolin. These can be purchased online or at a local cooking store.