There’s something deeply comforting about a bubbling dish of cheesy leeks — tender rounds of leek tucked into a silky, creamy cheese sauce, baked until golden brown and gooey on top. It’s the perfect side dish for a Sunday roast, Christmas dinner, or when you just fancy something cosy and rich. Think of it as cauliflower cheese’s elegant cousin — same comfort factor, but with a little more personality.
Melt 1 tablespoon of butter in a large pan. Add the leeks and saute over low-medium heat for 10 minutes until softened. Season with salt and freshly ground black pepper.
In the meantime, make the cheesy sauce.
Melt the butter, add the flour and stir over medium heat for 10-20 seconds to combine. Gradually pour the milk in, stirring continuously to avoid lumps from forming.
Carry on stirring and cooking the sauce until it thickens to a thin custard consistency. Take the sauce off the heat and whisk in the mustard, half of the grated cheese and a pinch of nutmeg.
Add the leeks to the sauce and mix to combine.
Scoop the leek mixture into an oven-proof baking dish, scatter the remaining cheese and breadcrumbs on top and bake for 15 minutes until the sauce is bubbling around the edges.