Active Time

　　20 min

　　Total Time

　　1 1/4 hr

　　Parsnips, celery root, and sweet potatoes bring depth to this unfussy gratin. Best of all, it requires no "arranging"—you just spread the root vegetables in the baking dish.

　　

Ingredients

Makes 12 servings

　　1 lb parsnips (about 4 medium)

　　1 medium celery root (sometimes called celeriac; 3/4 lb total)

　　1 lb sweet potatoes

　　1 1/2 lb russet (baking) potatoes

　　2 teaspoons salt

　　1 teaspoon finely chopped garlic

　　1/2 teaspoon black pepper

　　1/4 teaspoon freshly grated nutmeg

　　1/2 cup reduced-sodium chicken broth

　　1 3/4 cups plus 2 tablespoons heavy cream

　　

Special Equipment

an adjustable-blade slicer; a 3-quart gratin or other shallow flameproof baking dish (not glass; 13 by 9 inches)

　　

Step 1

Put oven rack in upper third of oven and preheat oven to 400°F.

　　

Step 2

Peel parsnips and cut crosswise into 3-inch lengths with a knife, then cut lengthwise around core into 1/8-inch-thick slices with slicer (discard core). Transfer to a large bowl.

　　

Step 3

Peel celery root and all potatoes (prepare russet potatoes last to avoid discoloration) and halve lengthwise, then cut crosswise into 1/8-inch-thick slices with slicer. Add to parsnips along with salt, garlic, pepper, nutmeg, broth, and 1 3/4 cups cream, tossing to combine. Transfer to gratin dish, spreading evenly.

　　

Step 4

Cut out a piece of parchment or wax paper to fit just inside gratin dish, then butter 1 side of parchment. Cover vegetables directly with parchment, buttered side down, then put dish in a shallow baking pan (to catch any drips). Bake until gratin is bubbling all over and vegetables are tender when pierced with a knife, about 50 minutes. Discard parchment.

　　

Step 5

Just before serving, preheat broiler. Drizzle top of gratin with remaining 2 tablespoons cream and broil 4 to 6 inches from heat until browned, 2 to 3 minutes.

　　Cooks' notes:

　　•Gratin, without final addition of cream (2 tablespoons), can be baked (but not broiled) 6 hours ahead and cooled completely, uncovered, then chilled, loosely covered. Reheat, covered, in a preheated 400°F oven until hot, about 30 minutes. Drizzle with cream and broil just before serving.

　　•If you're also making the chestnut, prune,and pancetta stuffing bake this gratin in lower third of oven while stuffing bakes in upper third.