With its beautifully browned topping and cheesy goodness, a gratin is always a crowd-pleaser, and it makes a wonderful side dish for roasted and grilled meats. Here, we feature leeks two ways: thin slices are baked into the cheese sauce, and deep-fried leeks form a crispy garnish. Look for goat’s milk cheddar at your local cheese shop or gourmet grocer, but you can substitute a high-quality cow’s milk cheddar if you like.
Cheesy Leek Gratin
- 4 Tbs. (1/2 stick) (2 oz./60 g) unsalted butter
- 2 Tbs. chopped fresh thyme
- 1/4 cup (1 oz./30 g) all-purpose flour
- 2 cups (16 fl. oz./500 ml) milk
- 1 1/2 cups (6 oz./185 g) shredded goat cheddar cheese
- Kosher salt and freshly ground pepper
- 6 leeks, white and light green portions, rinsed well and thinly sliced
- Canola oil for deep-frying
- 1/2 cup (2 oz./60 g) cornstarch
1. Preheat an oven to 375°F (190°C). Butter a large gratin dish or 8-inch (20-inch) square baking dish.
2. In a saucepan over medium heat, melt the butter. Add the thyme and cook, stirring occasionally, until fragrant, about 1 minute. Whisk in the flour and cook, whisking constantly, until golden, about 2 minutes. Slowly whisk in the milk, making sure each addition is fully incorporated before adding more. Add the cheese and cook, stirring frequently, until melted, about 2 minutes. Season to taste with salt and pepper.
3. Reserve 1 cup (3 oz./90 g) of the sliced leeks and add the remaining leeks to the saucepan, stirring to coat them with the cheese sauce. Transfer the mixture to the prepared baking dish. Bake until the top is browned and the leeks are tender, 25 to 30 minutes.
4. Meanwhile, fill a small saucepan halfway with canola oil and heat to 350°F (180°C) on a deep-frying thermometer. In a bowl, toss the reserved leeks with the cornstarch to thoroughly coat, separating the slices into individual rings. Working in batches, add the leeks and fry until golden and crispy, 1 to 2 minutes. Using a spider or a slotted spoon, transfer the leeks to a paper towel–lined plate and season with salt.
5. Remove the gratin from the oven and top with the fried leeks. Serve warm. Serves 6.
Williams Sonoma Test Kitchen