Anglesey Eggs

Ingredients

• 6 eggs egg
• 2 pounds russet potatoes – peeled and cut into chunks
• 2 teaspoons kosher salt
• 2 leeks leek
• 6 tablespoons unsalted butter
• 2.5 cups whole milk
• 2 tablespoons all-purpose flour
• 8 ounces Caerphilly cheese
• 1 teaspoon English mustard powder
• 0.5 teaspoon black pepper

Instructions

1. Heat the oven to 400°F. Trim the leeks, halve lengthwise, rinse away any grit, and thinly slice. Grate the Caerphilly cheese; set aside 2 oz (about 1/2 cup) for topping.
2. Place the eggs in a saucepan, cover with cold water by 1 inch, and bring to a boil. Reduce to a gentle simmer and cook 9–10 minutes. Transfer to an ice bath for 5 minutes, then peel and halve the eggs.
3. Meanwhile, put the potatoes in a large pot, cover with cold water, and add 1 teaspoon of the kosher salt. Bring to a boil and simmer until very tender, 12–15 minutes. Drain well and let steam-dry for 2 minutes.
4. While the potatoes cook, melt 2 tablespoons of the butter in a skillet over medium heat. Add the sliced leeks and a small pinch of the remaining salt; cook, stirring, until completely soft but not browned, 8–10 minutes. Remove from heat.
5. Return the drained potatoes to the pot. Add 2 tablespoons butter and 0.5 cup milk, then mash until smooth and fluffy. Fold in the cooked leeks. Season with 0.5 teaspoon of the remaining kosher salt and 0.25 teaspoon black pepper.
6. Make the cheese sauce: In a saucepan, melt the remaining 2 tablespoons butter over medium heat. Whisk in the flour and cook, whisking, 1 minute. Gradually whisk in the remaining 2 cups milk and simmer, whisking, until thick enough to coat the back of a spoon, 3–5 minutes. Off the heat, whisk in the mustard powder and 6 ounces of the grated Caerphilly until melted and smooth. Season with the remaining 0.5 teaspoon kosher salt and 0.25 teaspoon black pepper.
7. Assemble: Spoon the leek mash into a 2-quart baking dish and smooth the top. Nestle the halved eggs, cut side up, evenly over the mash. Pour the cheese sauce over the eggs and scatter the reserved 2 ounces grated Caerphilly on top.
8. Bake until bubbling at the edges and lightly golden, 15–20 minutes. For deeper color, broil 1–2 minutes more. Rest 5 minutes before serving.