Peel potatoes and cut them in smaller pieces.
Cook them in lightly salted water, covered, for about 10 minutes. Pour out the water.
Mash the potatoes in the pot.
Pour in the milk, preferably warm, a little at a time.
Mix the purée so that it is airy, with a fork or an electric mixer.
Add the salt, pepper and cardamom to taste.
Add the cheese of your choice and butter, and mix well.