Cook the macaroni following pack
instructions, adding the peas for the
final 3 mins. Drain, reserving a mug of
cooking water, then tip the macaroni
and peas back into the pan.
Heat grill to medium. Put the pan back
on the heat and tip in the mascarpone,
mustard and most of cheese. Mix well
and add enough of the reserved cooking
water to make a creamy sauce that coats
the pasta without it looking dry. Stir in the
ham and season to taste.
Tip into an ovenproof dish and scatter over the breadcrumbs and remaining
cheese, then grill for 5 mins until golden.