These bubbling, cheesy leeks are the ultimate side dish, perfect for a Sunday roast or family meal. Top with breadcrumbs for a crisp crust
Prep:20 mins
as a side
600g leeks (about 3 medium), trimmed and cut into 2cm rounds50g butter50g plain flour500ml milk100g mature cheddar grated1 tsp English mustard50g stale bread, blitzed to crumbs2 tsp thyme leaves
STEP 1Heat the oven to 220C/200C fan/gas 7. Tip the leeks into a steamer basket and steam for 6-8 mins until bright green and just becoming tender.STEP 2Meanwhile, heat the butter and flour together in a saucepan, stirring until you have a thick paste. Add the milk, a splash at a time, stirring continuously until all the milk has been added. Cook for 2-3 mins more until the sauce has thickened enough to coat the back of a spoon. Stir in most of the mature cheddar, the mustard and some seasoning.STEP 3Fold the steamed leeks into the cheese sauce, then tip everything into an ovenproof baking dish. Scatter over the breadcrumbs, thyme and remaining cheese, then bake for 20 mins until golden, crisp on top and bubbling at the edges. Leave to stand for 5 mins before serving.