Gratin with Potatoes and Leeks
Originating in France, the term gratin simply refers to the culinary technique of topping baked ingredients with a browned crust. We often think of the classic gratin as one made with potatoes–and potatoes are certainly one of the most plentiful root vegetables in February. A browned crust may be achieved by adding breadcrumbs, cheese, egg, and/or butter. I like the addition of leeks to the following recipe by NY Times contributor Melissa Clark. Increase the amounts proportionately, depending upon the size of your gratin pan (any shallow dish will do), and your preference for how thick you want each slice of the pie to be. In my opinion, there is never too much cheese, so you may want to add more–I like a combination of Parmesan and Gruyere–or add more garlic and garnish with fresh thyme. Experiment to see what you like best. You may bake this a day ahead; cover and chill; bring to room temperature and reheat.
2 tablespoons unsalted butter, more for greasing the pan
2 large leeks, trimmed and halved lengthwise
1 ½ pounds peeled Yukon Gold potatoes
1 teaspoon kosher salt
½ teaspoon ground black pepper
2 thyme sprigs
1 cup heavy cream
1 fat garlic clove, finely chopped
1 bay leaf
¼ teaspoon freshly ground nutmeg
¾ cup Gruyère, grated
- Heat oven to 350º degrees and butter a 2-quart gratin dish. Wash the leeks to remove any grit and slice thinly crosswise.
- Using a mandoline or sharp knife, slice the potatoes into rounds, 1/8-inch thick. Toss with 3/4 teaspoon salt and 1/4 teaspoon pepper. Layer the rounds in the 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, 5 to 7 minutes. Discard thyme and scatter the leeks over the potatoes.
- 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.
- Pour the cream over the leeks and potatoes and top with the Gruyère. * Cover with aluminum foil and transfer to the oven. Bake for 40 minutes, then uncover and bake until the cheese is bubbling and golden, 15 to 20 minutes longer. Let cool slightly before serving.
*Alternatively, you may leave the cheese off for now, cook the foil-covered potatoes a bit longer (about 50 minutes), remove foil, add cheese, and run it under the broiler for 5-8 minutes, until bubbly.