You’re wondering how to make mashed potatoes that everyone will love and you want to make them a full day ahead. What Kind of Potatoes Should You Use for Mashed Potatoes? Garlicky mashed potatoes? (How long to boil potatoes for mashed potatoes will vary based on the variety you use and the size you cut them. For ultra creamy mashed potatoes, transfer potatoes and garlic to a ricer or food mill.