Add the potatoes to a large pot of cold water. Season well with salt and bring to a boil. Simmer
until tender, 15 to 20 minutes.
Meanwhile, add the pancetta and onions
to a large skillet. Turn on the heat to medium-high, and saute until the pancetta
and golden. Add the milk
and season with salt and pepper. Heat until hot.
the potatoes well in a colander
. Use a food mill
the potatoes into the milk mixture. Fold together the potatoes with the hot milk, olive oil and chopped parsley.