What may seem like an odd combination actually makes a remarkable, delicately flavored soup. The fennel balances the sweetness of the pear perfectly, and its mild flavor is subtly enhanced by the addition of ground fennel seed at serving time.
For an elegant presentation, garnish each serving with a slice or two of caramelized pear and a sprig of feathery fennel frond.
Combine the fennel and water in a medium saucepan and bring to a boil. Reduce heat to medium, cover, and cook 15 minutes.
Add the pear nectar and cubed pears, and cook, covered, until pears are very soft and tender, about 15 minutes. Remove from heat and let cool for 10 minutes.
Transfer to a blender or food processor and purée until smooth. Pass the soup through a fine mesh sieve. Return to a clean pan and reheat over medium heat. Add the cream and bring to a simmer. Season to taste with the salt. If the soup seems too thin, cook for 5 to 10 minutes to concentrate the flavors.
Add the ground fennel just before serving; if you add it earlier, most of its flavor will dissipate.