SERVES 4
Another variation on the gratin theme (see here for the classic Dauphinoise Potatoes recipe), this one is flavored by mildly oniony leeks. To clean leeks, trim the root end and remove the dark tops (save them for stock), leaving just the white and light green parts. Cut the leeks into sections three to four inches long then cut those sections in half and immerse them in a bowl of water, fanning them out and leaving the leeks to float and the dirt to sink to the bottom. For particularly dirty leeks, repeat the cleaning for a second time with fresh water.
1½ pounds peeled Yukon Gold potatoes
Kosher salt and freshly ground black pepper
2 tablespoons unsalted butter, plus more for greasing the pan
2 large leeks, white and light green parts only, trimmed, washed and halved lengthwise, then thinly sliced crosswise
Leaves from 2 sprigs of thyme
1 cup heavy cream
1 large garlic clove, minced
1 bay leaf
¼ teaspoon freshly ground nutmeg
1 cup Asiago, grated
1 cup fresh breadcrumbs
2 tablespoons finely grated Parmesan
1 tablespoon unsalted butter, melted
HEAT oven to 400°F and butter a 2-quart gratin dish.
MELT the 2 tablespoons butter in a large skillet over medium heat. Add leeks, remaining salt and pepper, and thyme. Cook, stirring, until leeks are tender and golden, about 7 minutes.
ADD cream, garlic and bay leaf to the skillet, scraping up browned bits of leeks from the bottom of the pan. Simmer gently for 5 minutes. Stir in nutmeg.
WHILE the cream is heating, use a mandoline or sharp knife, and slice the potatoes into ⅛-inch thick rounds. Toss with salt and pepper. Layer half of the the rounds in the gratin dish. Top with all of the leeks and finish with a layer of the remaining potatoes. Pour the cream over the leeks and potatoes and top with the Asiago.
IN a small bowl, combine the breadcrumbs, Parmesan, and melted butter, and season with salt and pepper.
COVER the pan with aluminum foil and bake for 40 minutes. Remove the foil and sprinkle the breadcrumb mixture over the top. Return the gratin to the oven, uncovered, and bake an additional 12-15, or until until the cheese is bubbling and the top is golden brown. Allow to rest at least 10-15 minutes before serving.