Ingredients
1 tablespoon butter
1 tablespoon flour
2 cups chestnut puree
2 cups milk
6 cups chicken stock
1 tablespoon onion, finely chopped
1/4 cup celery, finely chopped
salt and pepper to taste
1 egg, beaten
3 tablespoons sherry or wine

Preparation
Melt butter in a large saucepan. Add the flour and stir until smooth. Add the chestnut puree, milk, chicken stock, onion, celery and salt and pepper and cook for 20 minutes, stirring occasionally. Just before serving, stir in the egg and sherry or wine.