First wash the potatoes under running water and remove the soil. Put them in a large pot with water and cook for about 40 minutes. Then drain and let cool briefly.
Peel the potatoes while they are still hot and press them into a large bowl using a potato ricer. Grate the parmesan and caciocavallo cheese. Then add to the potatoes together with the egg yolk and season with salt, pepper and freshly chopped parsley.
Now mix everything thoroughly until a soft and dry mass is formed. Now take a portion of dough of about 25g/0.9oz each and form into small balls.
Then prepare two bowls. In the first, add the eggs, salt a little and whisk thoroughly. Fill the second bowl with enough breadcrumbs.
Now place each ball in the beaten egg, drain well and then turn in the breadcrumbs. Then place on a baking tray lined with baking paper.
Once all the balls are formed, put the sunflower oil in a pot and heat it to about 170°C/340°F.
Now fry a few pieces at a time in the hot oil. Turn several times with a slotted spoon. As soon as they are golden brown all over, remove and transfer to a large plate lined with absorbent paper. Tip: To prevent them from cooling too much, until all the balls are fried, put them in the oven on keep warm.
Then serve the fried balls of potatoes warm and enjoy!Buon appetito!