Cut pumpkin into slices and remove seeds. Peel pumpkin and dice flesh. Peel, wash and chop the potatoes. Peel and chop onion. Fry pumpkin, potatoes and onion in hot clarified butter.
Pour in the stock, add the bay leaf and bring to the boil. Season with salt, pepper and lemon juice. Cook over medium heat for about 25 minutes. Remove bay leaf, puree soup and stir in cream.
Season if necessary. Serve as desired in a hollowed and carved pumpkin, sprinkle with pumpkin seeds.