Boil the potatoes until they are done (25-40 minutes depending on size). Finely grate the parmesan.
Mash the peeled potatoes or press them through the press and mix with the parmesan. Then pour in the milk slowly, stirring constantly, until the desired consistency is achieved. Season to taste with nutmeg, salt and pepper. Add the rosemary to the puree to taste and fold in with a hand blender.
Goes perfectly with Italian meat dishes and with my beef fillet in a puttanesca serrano coating.