Chef John's Root Vegetable Gratin


  • 2Yukon Gold potatoes, scrubbed and sliced 1/8-inch thick with peel
  • 1turnip, peeled and sliced 1/8-inch thick
  • 1rutabaga, peeled and sliced 1/8-inch thick
  • 1 small celery root, peeled and sliced 1/8-inch thick
  • 1parsnip, peeled and sliced 1/8-inch thick
  • salt, to taste
  • 3 cloves garlic, minced
  • 2 tablespoons butter
  • 1 ¼ cups chicken broth
  • 1 cup heavy cream
  • 1 tablespoon chopped fresh thyme
  • 1 pinch ground nutmeg
  • 1 pinch cayenne pepper
  • 2 teaspoons olive oil
  • ¼ cup finely grated Parmigiano-Reggiano cheese, divided
  • Directions

  • Step 1

    Preheat the oven to 375 degrees F (190 degrees C).


  • Step 2

    Bring a large pot of generously salted water to a boil. Add the vegetables, and cook uncovered for 3 minutes. Drain in a colander, then immediately immerse in ice water for several minutes until cold to stop the cooking process. Once the vegetables are cold, drain well, and set aside.

  • Step 3

    Cook garlic and butter in a large skillet over medium heat until garlic starts sizzling, about 3 minutes.

  • Step 4

    Stir in chicken broth, heavy cream, thyme, nutmeg, and cayenne pepper; cook until mixture begins to simmer, about 5 minutes.

  • Step 5

    Coat a 9×13-inch baking dish with olive oil and spread vegetables evenly over the oil.

  • Step 6

    Pour broth and cream mixture over vegetables and top with half of the grated Parmigiano-Reggiano cheese.

  • Step 7

    Cover baking dish loosely with aluminum foil, place on a baking sheet, and bake in the preheated oven for 40 minutes.

  • Step 8

    Remove baking dish from the oven and top with remaining Parmigiano-Reggiano. Bake uncovered until vegetables are browned, bubbling, and tender, about an additional 30 minutes.

  • Step 9

    Remove from the oven and let rest for 20 minutes.

  • Cook's Note:

    Root vegetable sizes and shapes vary. You’ll need enough to fill a 9 x 13-inch casserole dish 3/4 full.

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