Heat saucepan on low heat. Melt butter then sauté onion until tender. Steam potato, carrot and pumpkin until soft; about 30 minutes.
Meanwhile, put the crab claws into a steamer and top it up with ginger. Steam until claws turn orangey red.
When vegetables are ready, puree them in a food processor or blender. Put mixture in a saucepan then add the chicken stock and simmer for 15 minutes.
Add the cream then simmer for 5 more minutes lowering the heat if necessary, so it does not boil. Season to taste with salt and pepper. Sprinkle parsley and add crab claws. Serve immediately.