
Peel the potatoes and cut them into even-sized chunks. Place them in a large pot of salted cold water.
Bring the pot to a boil, then reduce the heat and simmer until the potatoes are tender, about 15-20 minutes.
Meanwhile, finely grate the Parmesan cheese and set aside.
Peel and finely chop the garlic cloves.
In a small saucepan, heat the double cream, butter, and chopped garlic over low heat until the butter is melted and the cream is warm. Do not let it boil.
Drain the potatoes well and return them to the pot. Mash them until smooth.
Gradually stir in the warm cream and garlic mixture into the mashed potatoes until well combined.
Fold in the grated Parmesan cheese and season with salt and freshly ground black pepper to taste.