In a large saucepan, melt the butter over medium heat. Add the onions and cele ry. Saute the vegetables until the onions are golden brown and the celery is s oft. Stir in the flour and curry powder. Cook for 5 minutes.
Place the mixture in a blender or food processor. Add the chicken, apples and 1 cup stock. Process until smooth. Return the mixture to the saucepan. Add t he remaining 7 cups stock and the bay leaf. Increase the heat to high to bring ingredients to a boil.
When the soup begins to boil, remove it from the heat, discard the bay leaf, an d refrigerate the soup for at least 1 hour. Before serving, stir in the chille d cream.