Potato and Leek Gratin

Ingredients:

• 5 Tbs. unsalted butter
• 4 lb. leeks, white and light green portions, rinsed well, cut into ¼-inch rings
• 1 ½ Tbs. kosher salt
• 1 tsp. minced fresh thyme
• ¼ tsp. freshly grated nutmeg
• ¾ tsp. freshly ground pepper
• 1 cup heavy cream
• 6 oz. Gruyère cheese, grated
• 3 oz. Parmigiano-Reggiano cheese, grated
• 3 lb. russet potatoes, peeled, cut into ¼-inch slices
• 3 Tbs. minced fresh chives

Instructions:

In a 12-inch nonstick fry pan over medium heat, melt 4 Tbs. of the butter. Add the leeks and salt, stirring to coat the leeks with the butter. Cover and cook, stirring occasionally, until the leeks are tender, about 20 minutes. Add the thyme, nutmeg, pepper and cream and simmer, uncovered, stirring occasionally, until thickened, about 15 minutes. Transfer to a bowl and let cool. Wipe out the pan and grease with the remaining 1 Tbs. butter.

Preheat an oven to 400ºF.

In a bowl, combine the Gruyère and Parmigiano-Reggiano cheeses. Layer one-third of the potatoes in the fry pan and spread one-third of the leek mixture on top. Sprinkle with one-third of the cheeses, then 1 Tbs. of the chives. Repeat the layering 2 more times, reserving 1 Tbs. of the chives.

Cover the pan, transfer to the oven and bake for 45 minutes. Remove the lid and continue baking until the potatoes are tender and the crust is golden brown, about 30 minutes more. Sprinkle the remaining 1 Tbs. chives on top. Let the gratin stand for 15 minutes before serving. Serves 8 to 10.

Originally found at http://www.williams-sonoma.com/recipe/potato-leek-gratin.html