First of all, wash the potatoes well, place them in a saucepan with plenty of cold water and cook over high heat for about 30 minutes after boiling: when they are very soft, drain them, peel them and mash them while they are still hot.
Remove skin and any bones from the fish, then cut it into pieces.
Combine fish, egg, garlic, parsley and cheese in a blender and blend, then add the mixture thus formed to the potatoes and mix.
If the consistency seems too soft, add a little breadcrumbs.
Form balls by taking 1 knob of mixture at a time and dipping them in breadcrumbs.
Then fry the croquettes in plenty of already hot oil, then drain them with a slotted spoon on kitchen paper.
The cod meatballs are ready, all you have to do is serve them immediately, while they are nice and hot.