In a heavy saucepan over low heat, gently sweat the sliced onion in the butter until soft and translucent.

Add the sliced Jerusalem artichokes to the onion.

Cook, covered, for 10 minutes, stirring occasionally.

Pour in 600ml/1pint water and add the milk.

Season with salt and ground white pepper to taste.

Simmer slowly, making sure not to boil to prevent the milk from curdling.

Use a blender or food processor to purée the soup until smooth.

Taste and adjust seasoning if necessary.

Reheat gently.

Serve the Creamy Jerusalem Artichoke Soup, garnished with a drizzle of olive oil or a sprinkle of fresh herbs if desired.