Wash the leeks, slice them into half rings, and place them in a different saucepan of boiling water. Boil until softened (usually 8mins). Place in an ovenproof dish.
Step 3:
Melt butter in a saucepan and add the flour, gradually adding milk. Keep stirring to avoid lumps. Simmer for 5mins.
Step 4:
Preheat the grill to high.
Step 5:
Add the mustard and half of the cheese to the butter, flour & milk, simmer for 3 mins, then season with black pepper and salt. Slice the ham into thin strips, add to a saucepan, and simmer for 2 minutes.
Step 6:
Drain the pasta and mix with leeks in an ovenproof dish. Quarter the hard-boiled eggs and place them on top.
Step 7:
Pour the contents of the saucepan on top of the leeks & pasta. Sprinkle the breadcrumbs and the remaining cheese on top. Grill for 10 minutes or until the top turns golden.