Cauliflower with Béchamel sauce (white sauce)

Preparation

• Clean the cauliflower and cook it water
  when it's cooked keep the water
  take a pan and melt the butter in it
  add some flour it it (till the butter is dry)
  poor little by little some water of the cauliflower in it
  mix till you have a thick béchamel or white sauce
  add the grated cheese and mix
  add salt, pepper and nutmeg
  
  put under the grill in the oven for a few minutes