Cut a slice about 3 cm thick from the cauliflower and cook it for 2 minutes, cool with ice water.
Melt the butter in a saucepan and add the flour. Let the flour cook while stirring. Add the milk little by little and stir well, so that all the lumps disappear. When all the milk has been added, let the mixture boil for a while and then remove it from the heat. Then add the cheese and stir all the way through the sauce. Grill the blanched cauliflower over the hot binchotan until it begins to colour and is warm. Serve with the cheese sauce and, as a garnish, warm the cauliflower in a hot oven or on the grill.