Finely chop the onion, celery and leek.

Fry gently in the butter, softening, but ensuring they do not colour.

Add the chopped cauliflower. Add the stock, the mustard powder and the thyme.

Simmer gently for 30 minutes.

Whizz in a food processor of blender. Pass through a fine strainer.

Return to a clean pan, finish with the cream and the smoked cheddar.

Season with salt and pepper.

For added interest and flavour, sprinkle with grated smoked cheddar and brown under the grill or with a blow torch.