Serves:
6
Active Time:
40 Minutes
Start to Finish:
1 Hour Leek and Mushroom Gratin
This rich gratin employs one of our favorite techniques: the leeks are cooked in a skillet covered not with a lid but with a round of parchment paper placed directly on the vegetables. This lowtech method allows just enough steam to escape while keeping the vegetables perfectly moist. A bit of lemon zest helps balance the gratin’s richness. This is delicious with roast chicken, squab, or pork chops.
Ingredients
3⁄4 stick (6 tablespoons) unsalted butter
1 cup fine dry bread crumbs
1⁄4 pound Gruyère, finely grated on small teardropshaped holes of a box grater (about 2 cups)
1⁄2 cup finely grated Parmigiano-Reggiano
2 teaspoons finely chopped garlic
1 tablespoon finely chopped fresh flat-leaf parsley
Salt and freshly ground black pepper
3 pounds leeks, root ends trimmed
2 tablespoons all-purpose flour
1 1⁄2 cups Chicken Stock (page 153) or store-bought reduced-sodium broth
1⁄8 teaspoon freshly grated nutmeg
1⁄2 teaspoon finely grated lemon zest
1 pound cremini mushrooms, trimmed and thinly sliced
SPECIAL EQUIPMENT: a 1 1⁄2-quart gratin dish or shallow baking dish; parchment paper
Instructions
MELT 2 TABLESPOONS BUTTER in a small saucepan over low heat; cool.
Toss melted butter with bread crumbs, cheeses, garlic, parsley, 1⁄4 teaspoon salt, and 1⁄8 teaspoon pepper in a bowl until combined.
Trim each leek to an 8-inch length (reserve tops for another use if desired). Halve leeks lengthwise and cut crosswise into roughly 1-inch pieces. Wash leek pieces in a large bowl of cold water, agitating them, then lift out and transfer to another bowl. Repeat with fresh water and drain leeks well.
Melt 1 tablespoon butter in a 1- to 1 1⁄2-quart heavy saucepan over moderate heat. Add flour and cook, whisking, for 1 minute to make a roux. Add stock in a slow stream, whisking, and bring to a boil, whisking. Add nutmeg and zest and boil, whisking, for 1 minute. Remove from heat.
Put a rack in middle of oven and preheat oven to 400°F. Butter gratin dish.
Melt 1 tablespoon butter in a 12-inch heavy skillet over moderately low heat. Add leeks, 1⁄4 teaspoon salt, and 1⁄4 teaspoon pepper, cover leeks directly with a round of parchment paper, and cook, stirring occasionally, until liquid is absorbed and leeks are tender and just beginning to brown, 10 to 15 minutes.
Meanwhile, heat remaining 2 tablespoons butter in a large heavy skillet over moderate heat until foam subsides. Add mushrooms, 1⁄4 teaspoon salt, and 1⁄4 teaspoon pepper and cook, stirring occasionally, until liquid is absorbed and mushrooms are just beginning to brown, about 15 minutes. Remove from heat.
Remove parchment from leeks and stir in mushrooms. Transfer mixture to gratin dish, spreading it evenly. Pour sauce over vegetables and top with crumb mixture. Bake until gratin is bubbling and topping is golden, about 15 minutes.
COOK’S NOTE
The gratin can be assembled, without the bread crumbs, up to 8 hours ahead. Cool, uncovered, then refrigerate, covered. Bring to room temperature, stir, and top with the bread crumbs before baking.