Cook the pasta
according to the packet directions, drain.
Meanwhile, fry (sauté) the onion in the butter for 3
minutes until soft and lightly golden.
Stir in the
flour then blend in the milk until smooth. Add the
bay leaf, bring to the boil and cook for about 2
minutes, stirring all the time, until thickened.
Remove the bay leaf. Stir in the mustard and season
to taste. Stir in the macaroni then add a third of
the cheese and all the remaining ingredients. Taste
and reseason, if necessary.
Pile into an ovenproof
dish. Top with the remaining cheese and bake in the
oven at 200°C/400°F/gas mark 6 for about 25 minutes
until bubbling and golden.