Leek and Spring Onion Gratin
Lighter than a potato gratin, but still luscious from heavy cream and cheese, this allium-rich dish has a crunchy bread crumb and anchovy topping to take it over the top. If you can’t find spring onions — newly harvested onions often sold with the green stems still attached — use regular onions or shallots. Or try red onions for a shot of bright color among the soft greens and golds in the pan. Serve this as a side dish with grilled or roasted meats or fish.
- Serves: 6 persons
- 3scallions, thinly sliced
- 2stalks green garlic or 2 garlic cloves, thinly sliced
- ½teaspoon fine sea salt, more as needed
- ¼teaspoon black pepper
- 3leeks, white and light green parts only, halved lengthwise and cut into 1-inch pieces crosswise
- 2spring onions, cut into 1-inch wedges
- 3tablespoons butter, cut into cubes
- 5anchovies, minced
- ⅓cup grated Parmesan cheese
- ⅔cup panko bread crumbs
- 1teaspoon thyme leaves, finely chopped
- 1teaspoon finely grated lemon zest
- Pinch of red pepper flakes
- 1tablespoon extra-virgin olive oil, plus more for drizzling
- 4ounces Gruyère, coarsely grated
- 1cup heavy cream
Step 1Place a rack in the top third of oven and heat to 400 degrees. In a medium bowl, toss scallions, green garlic, salt and pepper.
Step 2Heat a 12-inch cast-iron skillet over medium heat. Arrange the leeks cut-side down in the skillet, then scatter spring onions in the gaps. Sprinkle a little more salt on top, then spread scallion mixture in an even layer in pan. Pour in 1/4 cup water and top with butter.
Step 3Cover and and simmer on low heat until vegetables are soft, 20 to 25 minutes.
Step 4Uncover the pan, turn heat to medium-high and cook until liquid is evaporated and edges are starting to brown and sizzle, 5 to 10 minutes longer.
Step 5Meanwhile, in a small bowl, rub together anchovies, Parmesan, panko, thyme, lemon zest and red pepper flakes. Drizzle in oil and toss to combine.
Step 6Sprinkle Gruyère evenly into skillet over leeks, pour in cream, then top with the bread crumb mixture. Drizzle with a little more oil. Transfer to oven and bake until golden and bubbly, 15 to 20 minutes. Cool slightly, then serve warm.