1 small leek
1 tbsp butter
750g firm zucchini (courgettes)
handful fresh basil
salt and white pepper
500g chicken or vegetable stock (unsalted)
75g mild blue cheese
1/2 cup cream
Trim the leek, discard the green top and wash the white part carefully, making sure to remove grit or mud lurking between the layers. Slice thinly.
Heat the butter in a large saucepan and, as soon as it stops foaming, add the leek. Cook on a low heat, stirring regularly, for 5-8 minutes, or until it softens. Meanwhile, wash the zucchini well, top and tail and slice thinly. Add to the softened leek and fold over to coat with melted butter.
Tear the basil into sprigs, reserving four for garnish, and stir into the mix. Season cautiously with salt and white pepper, because blue cheese can be quite salty.
Cook, stirring regularly, for about 10 minutes, then pour the stock over the top. Bring to the boil, cover and simmer for 30 minutes.
Discard any rind from the blue cheese, cut into small pieces and stir into the soup until it just melts, saving a little for garnish. Tip the soup into a food processor, working in batches if necessary, and process to well-mixed thickness. For a totally smooth finish, use the back of a large spoon to force the puréed soup through a sieve. Pour the soup back into the saucepan, heat, then stir in most of the cream, but don't boil. Check the seasoning, then serve in warm bowls. Drizzle the remaining cream over the top and garnish with basil sprigs and reserved cheese.