Ombre Root Vegetable Gratin

 Source (check out the photo)!

Ingredients

Unsalted butter, for greasing 
2 cups heavy cream
3 garlic cloves, minced
1 small shallot, minced
1 1/2 teaspoons kosher salt
1/2 teaspoon freshly grated nutmeg
1/2 teaspoon pepper
1 3/4 cups freshly grated Parmigiano-Reggiano cheese (5 ounces), divided
1 pound red beets, peeled and sliced on a mandoline 1/16 inch thick
1 pound sweet potatoes or garnet yams, peeled and sliced on a mandoline 1/16 inch thick
1 pound Yukon Gold potatoes, peeled and sliced on a mandoline 1/16 inch thick
1 pound turnips, peeled and sliced on a mandoline 1/16 inch thick

Method

Preheat the oven to 375°F. Lightly butter a 9- x 13-inch baking dish. In a medium bowl, whisk the cream with the garlic, shallot, salt, nutmeg, and pepper. Stir in 1 cup of the grated cheese.

In a large bowl, gently toss the beets with one-fourth of the cream mixture. Arrange the beets in the baking dish in an even layer, overlapping them slightly. Scrape any remaining cream from the large bowl over the beets. Repeat this process with the sweet potatoes, potatoes, and turnips, using one-fourth of the cream mixture for each vegetable. Press a sheet of parchment paper on top of the turnips, then cover the dish tightly with foil.

Bake the gratin for about 1 hour and 30 minutes, until the vegetables are tender. Uncover and top with the remaining 3/4 cup cheese. Bake until golden on top, about 15 minutes longer. Transfer the gratin to a rack, and let cool for at least 15 minutes before serving.