Rich ham and cheese toastie

Method

1. Heat the milk in a saucepan. In a separate saucepan, melt the butter, then whisk in the flour. Whisk in the hot milk and continue whisking as the sauce comes to the boil, then cook over a medium heat for 2 minutes to cook out the flour (removing the flour’s raw taste for a nuttier flavour). Take off the heat, then stir in the mustard and most of the cheddar, reserving about 70g.
2. Heat the grill to high. Drizzle the sourdough with olive oil and arrange on a large baking sheet. Toast under the grill on one side until golden. Turn over, spread some of the cheese sauce over the sourdough, then add a layer of ham. Cover with the remaining sauce, then sprinkle over the reserved cheddar.
3. Put back under the grill to melt the cheese. Drizzle with a little Worcestershire sauce or chilli sauce – whichever you prefer – then serve immediately