Melt the butter or margarine and add the celeriac. Stir and then sweat for 3-4 minutes. Add the leek and garlic and cook for a further 3-4 minutes and then add the chopped celery and stock. Gently simmer with the lid on for 15 minutes or until the celery is just soft. Remove from the heat and leave to cool.
Liquidize and then sieve if a smoother texture is desired. Stir in the milk and cheese and reheat until the cheese has dissolved, taking care not to let it boil.
Garnish with croutons and ½ tsp finely chopped celery leaf.
If preferred the cheese can be omitted from the soup and garnished instead with the cheesy croutons for a less intense flavour.
Cheesy croutons: Mix the bread cubes, olive oil and grated cheese in a bowl. Scatter onto a baking tray and cook for 20 minutes at 180C/350F/Gas 5. Cook for another 10 minutes if not golden brown. Cool and store in an airtight container for up to a week.
Our thanks to www.fenlandcelery.com for providing this recipe.