Leek macaroni cheese

Throwing caution to the wind, I nipped upstairs whilst the leeks were very slowly softening and when I came down not 2 minutes later the leeks had started to colour - which Nigel said I was to avoid! I think I saved it though and as I'd used all the leeks given to me my friend from her allotment I added them anyway.  I'm incapable of having mac n cheese without some bacon so this is my leek and bacon macaroni cheese.