Fill a large bowl with cold water. Peel the potatoes and plunge them into the water as you finish peeling them. Fill a large saucepan half way with water. Cut the potatoes into ½ inch pieces. Add them to the saucepan as you cut to keep them from oxidating and turning brown. Bring the potatoes to a boil over medium heat. Lower the heat and cook for 20 minutes or until they are fork-tender. Drain the potatoes in a colander. Use a Foley Food Mill for a light and silky consistency. Add the butter, cream and salt.