To make the cheese topping start by melting the butter in a heavy bottomed pan, add the flour to make a roux and cook out over a low heat for 2 minutes.
Gradually add the milk beating well between each addition to avoid lumps.
Bring to the boil and add the cheese, mustard and Worchester sauce – mix this well and season.
Toast the bread on one side then top the untoasted side generously with Caramelised Onion Chutney.
Top with the cheese mixture and place back under the grill until golden and bubbling.