Boil the potatoes, peel them and mash them well with the butter and yolks egg. Add crushed stock, flour, seasoning to taste and 2-3 tablespoons of grated cheese. Stir well.
Shape mixture into small balls and arrange them in a large pan. While forming all the balls, they need to cool. Heat the oil for frying.
Roll each ball in a little fine corn flour and and drop to fry until light brown.
Deep-frying is most convenient.