Using a sharp knife, score the chestnuts on the base then microwave them on high for a couple of minutes (or bake at 200 degrees C or 400 degrees F for 15 minutes) until the shells open.
Peel while warm.
Melt the butter and oil in a pan over a medium high heat.
Add the carrots, onion, celery, thyme, parsley and bay leaf and stir for 4 or 5 minutes.
Add the stock, ginger, chestnuts, salt and pepper, cover and simmer until the chestnuts are tender.
This will take about 20 minutes.
Remove the herbs and keep 2 tablespoons of the vegetable and chestnut mixture on one side.
Process the vegetables and stock in a blender until smooth then put it back in the pan.
Add the pouring cream and warm through without boiling. Ladle the soup into 4 bowls, top withe the reserved vegetable and chestnut mixture and sprinkle some parsley on the top.