Peel and chop the potatoes. Add to a pot and cover with water. Boil for about 12 minutes or until soft.
While the potatoes cook, melt butter in a small sauce pan. Add chopped garlic, rosemary, salt, & pepper.
Once soft, drain the potatoes & mash in the butter mixture, parmesan and half of the milk & cream. Mash until smooth adding more milk & cream as you go.