1Boil cauliflower, broccoli and leek for 5 mins with half a teaspoon of salt, then drain off the stock and put in a separate bowl.
2Put the vegetables in an oven proof dish.
3To make the sauce, melt the butter and put all the ingredients except cheese, nutmeg and cayenne pepper stirring all the time.
4Gradually add the stock to the flour stirring constantly until a desired smooth texture and add all the cheese leaving 100g for later.
6Pour the sauce on cauliflower, and lay the remaining mature Cheddar slices on top. Sprinkle small amount of nutmeg and cayenne pepper.
10Bake in the oven for about 1 hour on gas no.3 until the top become golden brown.
Make some potatoes, pasta or cod fillet for main meal and enjoy it :)