Peel the potatoes and put them in a pot. Cover the with water. Add a bit of salt and the smashed garlic cloves.
Cover and bring to a boil, then simmer with lid loosely on until the potatoes are tender, about 25 minutes.
Drain the water out of the pot. Add the butter and milk and mash well.
Add the parmesan and salt and pepper to taste and stir until combined.