Add olive oil to the saucepan, add the celery, carrot, onion, bay leaf and stock. Bring to the boil then simmer for about 20 minutes
In a separate frying pan, add some olive oil and add the mushrooms cooking them gently until they brown. Add the chopped chestnuts and cook for a few minutes.
Reserve some of the mushroom/chestnut mix, and add the remainder to the stock in the saucepan. Simmer for another 5 minutes
Remove the bay leaf, season and blend until smooth. Serve and garnish with some of the reserved mushrooms and a handful of pine nuts.