Cut 100 g of the chestnuts into small cubes for the soup garnish, chop the rest coarsely. Cut off the spring onions and sweat them with the chopped chestnuts in vegetable fat, deglaze with vinegar, port wine and chicken soup and simmer the chestnuts until soft.
Blend the chestnuts with the clear soup and whipping cream in a kitchen blender and pass through a sieve, return to the saucepan form and season with salt, pepper and a pinch of nutmeg. Roast the diced chestnuts in vegetable fat and add to the soup. Finally, blend the soup again with a spoonful of whipped cream.
If you do not have peeled chestnuts, or if you have collected them yourself, cut them all around and roast them on a baking tray at 200°C for 10 to 15 minutes, remove the skin while they are still warm. The colder they get the worse they get rid of the shell.