Peel avocado and chop the flesh coarsely. Place it into a blender container.
Add chicken broth, chile powder and cumin; blend until smooth. Pour the mixture
into a saucepan and cook over very low heat until very hot. Do not allow it
to boil. Pour the avocado mixture into a bowl and allow to cool. Stir in the
cream, add the salt and cayenne pepper, and chill thoroughly in the refrigerator.
Pour the soup into individual serving bowls, sprinkle with a little cayenne
pepper, and garnish with cilantro sprigs.