Creamy Cheesy Leek Gratin

Braised Leeks

• Leeks, trimmed and cut into 1.5-inch pieces, then halved lengthwise (reserve the tops)
• Chicken stock
• A few sprigs of fresh tarragon
• A little butter
• Salt
• A splash of sherry vinegar

Cheese Sauce

• The reserved leek tops, finely sliced
• Butter
• Salt and black pepper
• Fresh tarragon
• Flour
• Milk
• Grated nutmeg
• Mustard powder
• Comte cheese, grated (plus more for topping)

Directions

• Trim the leeks and cut into about 1.5-inch pieces, then slice those in half. Wash well to remove any grit and arrange snugly in a baking dish.
• Heat some chicken stock with a few whole sprigs of tarragon and a little butter (add salt if the stock is unsalted). Lightly salt the leeks and add a splash of sherry vinegar, then pour the stock over the leeks.
• Bake at 325F, checking after about 30 minutes, until the leeks are tender.
• Meanwhile, make the sauce: melt butter in a pan, add the finely sliced leek tops with a good pinch of salt and black pepper. Cover and cook on medium-low about 20 minutes.
• Stir in some more tarragon and a little flour; cook a couple of minutes. Add milk a little at a time until you reach a pourable sauce consistency.
• Season with salt, grated nutmeg and a little mustard powder, then stir in the grated Comte until melted.
• Spoon the cheese sauce over the baked leeks, smooth it out, and top with a little more grated cheese.
• Bake at 400F, checking after about 30 minutes, until bubbly and golden. Let it rest a minute before serving.

Method transcribed from the video (rough). From Corre Larkin (cocolarkincooks) on Instagram.