Gently fry the finely chopped onion over a low heat in olive oil for about 5 minutes or until it’s soft, but before it changes colour.
Add the cubed celeriac, turn up the heat and stir-fry for a couple of minutes. Pour the chicken stock over to cover and simmer for half an hour.
Blend and season to taste and add the cream.
Serve with cubes of blue cheese, chopped hazelnuts and small pieces of raw apple.