To Cook Chestnuts: With a sharp knife, slice an "X" across each chestnut. Place chestnuts in a single layer on a jelly roll pan. Pour 1/4 cup water into the pan. Bake in a preheated 450 degrees F (230 degrees C) oven for 10 minutes. When cool enough to handle, shell and peel.
In a large saucepan combine the chicken stock, shelled chestnuts and chopped onions. Place the parsley sprigs, cloves and bay leaf in a spice bag and add to the chicken stock mixture. Simmer over medium-low heat for 45 minutes.
Discard the spice bag and puree the chestnut mixture in a food processor or blender. Add the heavy cream, sugar and salt and pepper to taste. Return mixture to saucepan and gently heat through. To serve to with a dollop of unsweetened whipped cream, a bit of chopped parsley and some cooked chopped chestnuts just before serving. High quality vegetable broth can be substituted for the chicken broth.