Toast the bread in
a toaster. Meanwhile, mix the cheese
sauce, onions and a grind of pepper
together in a small bowl.
Transfer the toast to
a non-stick grill rack and drape the
ham over each slice. Next, spoon the
cheese sauce onto the ham and
spread it around with the back of the
spoon. Scatter the grated cheese over
the sauce, then pop the rarebit under
a hot grill until the cheese turns bubbly
and golden. Cut each slice in half and
serve while still hot.