Potato and Celery Root Gratin with Leeks

Celery root, also known as celeriac, has a knobby exterior that is best peeled (carefully!) with a paring knife

8–10 servings

Recipe by Susan Spungen

Photograph by Christopher Testani

November 2011

Ingredients

3 cups heavy cream

2 garlic cloves, peeled

1 sprig thyme plus 3 tsp. fresh thyme leaves, divided

2 tablespoons (1/4 stick) unsalted butter, divided

3 leeks, white and pale-green parts only, halved lengthwise, thinly sliced crosswise

Kosher Salt

2 pounds russet potatoes, peeled, very thinly sliced crosswise (1/8" thick)

1 pound celery root, peeled, very thinly sliced crosswise (1/8" thick)

2 cups grated Gruyère

Freshly ground black pepper

Preparation

Preheat to 350°. Heat cream, garlic, and thyme sprig in a medium saucepan just until bubbles begin to form around edge of pan. Remove from heat; set aside to steep.

Melt 1 Tbsp. butter in a medium skillet over medium heat. Add leeks; season with salt and cook, stirring often, until tender (do not brown), 10–12 minutes. Transfer to a small bowl and set aside.

Butter a 3-qt. gratin dish with remaining 1 Tbsp butter. Layer 1/3 of potato slices and 1/3 of celery root slices evenly over bottom of baking dish. Cover with 1/3 of leeks, then 1/3 of Gruyère. Sprinkle with salt, pepper, and 1 tsp. thyme leaves. Repeat layers twice more. Strain cream mixture into a medium pitcher and pour over vegetables.

Set gratin dish on a large rimmed baking sheet and cover tightly with foil. Bake for 1 hour. Carefully remove foil; continue baking until top is golden brown and sauce is bubbling, 25–30 minutes. 

DO AHEAD: Can be made 2 hours ahead. Let stand at room temperature. Tent with foil and rewarm in a 300° oven until hot, about 20 minutes

Read More http://www.bonappetit.com/recipes/2011/11/potato-and-celery-root-gratin-with-leeks#ixzz1bkkaYuZF