Cook the macaroni following pack
instructions, adding the cauliflower for
the final 4 mins.
Melt the butter in a pan, then stir in the
flour and mustard powder and cook for
2 mins. Gradually add the milk, stirring
all the time to get a smooth sauce. Add
three-quarters of the cheese and some
seasoning to the sauce.
Drain the macaroni and cauliflower and
stir into the cheese sauce. Transfer to an
ovenproof dish, then sprinkle over the
remaining cheese and flash under a hot
grill until golden and bubbling. Serve with
a green salad, if you like.