Begin by scoring the frankfurters diagonally and then scald them with boiling water.
Next, mash the boiled potatoes until they are smooth and creamy, then combine them with butter, one egg, mozzarella, parsley, salt, and starch.
Form the mashed potato mixture into croquettes, placing slices of cheese and frankfurters inside each one.
Coat the croquettes in flour, dip them in egg, and then roll them in breadcrumbs.
Finally, fry the croquettes until they are golden brown on all sides.
