Cheese and Mustard Crust Gammon Joint

Bought this from asda and thought that the honey glaze would be a bit boring so I've tried to create my own mustard and cheese crust.

Cheese sauce:

15g Butter

15g plain flour

120ml milk
40g grated cheese (all cheddar or a mixture of other cheeses depending on your taste)
tiny pinch of salt
sprinkle of black pepper

Crust:
1 crust slice from a loaf of bread
35g mixed grated cheese
sprinkle of herbs (use what ever you have in the cupboard, I used thyme, parsley and italian seasoning)
2 tsp wholegrain mustard
1 tsp olive oil

The sauce and crust can be made in advance ( not the day before but earlier in the evening)

Blitz the bread in a food processor until it looks like breadcrumbs, don't worry if there are a few of large lumps.
While the processor is running add the herbs and cheese then 1 spoon of the mustard then the oil then the rest of the mustard.  After a few seconds it should have a crumble like texture.  You can leave this in the processor with the lid on until ready to use.  You can put the bowl in the fridge to keep it fresh.

For the sauce - melt the butter in a small saucepan until melted.

Take off the heat and stir in the flour.  Keep stirring until you are left with a thick paste. 

Return to the heat and keep stirring while it cooks for about a minute.  Remove from the heat again and add the tiniest bit of milk and stir until combined.  Keep adding small amounts of milk until it becomes a thick sauce then add the rest of the milk.  Return to the heat and simmer whilst stirring until thickened.  Don't stop stirring or it will become lumpy.  The cheese can now be added off the heat.  I have used a mixture of parmesan and mild cheddar.  Stir vigorously until melted into a smooth creamy sauce.  If you  find it is taking a while to melt you can return to the heat for a second or two.  Add your seasoning and stir.  I used the tiniest amount of salt then tasted to make sure it wasn't too salty.  Cover and set to one side.

The Gammon joint I bought was a ready to roast 465g and required 40-45mins at 190C so I cooked it on it's own for 20 minutes then I spread with the sauce and covered with the crumble topping.

 I baked it for the remainder if the time.  Remove from the oven and leave to rest for 5 minutes before carving.

We served with potato wedges and veg.  I had some of the sauce left over so reheated this and served on the side.