Cut the potatoes into pieces and cook them quickly in salted water keeping them slightly firm.
Drain, dry out in the oven then pass them through a sieve. Replace in the pan and add 100 g 3½ oz) butter per 1 kg (2¼ lb) potatoes; season with salt, pepper and grated nutmeg and mix well on the stove. Remove from the heat and mix in 4 egg yolks and 1 whole egg.
Divide the mixture into 60 g (2 oz) pieces and mould round, cork or pearshape using flour. Egg and breadcrumb them and deep fry approximately 5 minutes before serving.