Cut a leek into thin disks and soak in cold water for half an hour or so, to remove any soil trapped between the layers.
Drain and sauté in a knob of butter until softened. Season with freshly ground black pepper. Cook macaroni according
to the packet directions, drain and tip into a casserole dish. Chop cooked ham into bite-sized pieces and mix in with
the macaroni. Stir in the cooked leeks, mixing everything together. Make a cheese sauce using sharp cheddar and pour
this over the macaroni, ensuring everything is covered, sprinkle the top with more grated cheddar and bake in a 180°C oven
for about 30 minutes, until the sauce is bubbling and the top is golden. Serve with a simple side salad.