Fry chopped leeks in a large frying pan in a knob of butter and olive oil over a gentle heat, so as not to burn, for five mins or until soft. Putting a lid on top helps to soften them quicker.
Chop up the cauliflower into slices and add to the pan with the leeks and pour over the stock and leave to gently simmer with lid on until soft-about 15/20 mins .Be careful not to let the veg burn.
Meanwhile melt butter in a saucepan and then add flour and mix together to form a roux. Add the milk and using a whisk break down and disperse the roux within the added milk and bring to the boil while whisking. It will form lumps but if you keep whisking they will disappear and a shiny white sauce will appear. Keep the faith.
Add the cheese and simmer gently for ten mins. Either use a blending stick or a food processor to whizz the cheese sauce and contents of the vegetable pan together and season carefully to taste. I like to be generous with the pepper here. Add more stock or water if the soup is too thick.
Apply to Middle-Aged Jowls...
Notes
I like to be generous with the black pepper here. I love a little peppery kick in the colder weather.