Peel pears under cold, running water with a vegetable peeler, leaving them whole with stems intact. Brush with lemon juice to prevent discoloration. In a large saucepan, combine the pear nectar and pears. Cook over low heat for 20 to 25 minutes, testing frequently to see if pears are cooked. When cooked, but still firm to the touch, carefully remove the pears from the juice and chill, reserving the cooking liquid. When ready to serve, rapidly boil the cooking liquid until reduced to about 1/4 cup. Add the chocolate chips and stir until the chocolate melts and the sauce is smooth. To serve, spoon about 1 tablespoon of the chocolate sauce and 1 tablespoon of the raspberry sauce onto each plate. Place the pear, standing up on the bed of sauce.
For Raspberry Sauce:
In a food processor or blender, puree the berries. Strain through a fine sieve, pressing with the back of a spoon to remove as much liquid as possible. Makes 1 1/2 cups