Wash the potatoes well without peeling them, then boil them for 25 minutes in boiling and slightly salted water.
Drain the potatoes, peel them, mash them with a potato masher and let them cool.

Meanwhile cook the cotechino. I used a pre-cooked cotechino to save time: put it with all its aluminum wrapping in a pot full of cold water, bring to a boil and then calculate 20 minutes of cooking.
Then remove the package, remove the liquid that has formed inside, peel the cotechino and cut into 12 pieces.

Once the potatoes have cooled, add egg yolk, cheese, salt and nutmeg and mix.

Take back the cotechino and wrap each cube with the potato mixture.
Pass the croquettes so formed first in the flour, then in the beaten egg and finally in the breadcrumbs.
Fry in hot oil, stirring them from time to time until they brown evenly.

Your potato croquettes with a heart of cotechino are ready: serve immediately!