A Phenomenal Potato Purée & Mashed Potato Sandwich

Butter makes or breaks mashed potatoes, and this style of mashed potato does not go light on the butter. These potatoes turn out silky smooth and take a little more time and care than most simple mashes, but they are truly phenomenal. According to my Irish grandmother, when you have leftover mashed potatoes, you should always make a kick-ass mashed-potato sandwich the next day.