Peel potatoes and place them in a large pot with a large amount of water. Bring water to a boil, and let the potatoes boil until soft. Drain and mash well.
In a large mixing bowl, combine 8 cups mashed potatoes, cream, butter, salt, and sugar. Cover potatoes and refrigerate over night.
Mix flour into the mashed potatoes and roll the mixture into balls about the size of tennis balls, or smaller depending on preference. Keep balls of dough on plate in the refrigerator.
Taking one ball out of the refrigerator at a time, roll dough balls out on a floured board. To keep the dough from sticking while rolling it out, it helps to have a rolling pin with a cotton rolling pin covers.
Fry the lefsa in a grill or in an iron skillet at very high heat. If lefsa brown too much, turn the heat down. After cooking each piece of lefsa place on a dishtowel. Fold towel over lefsa to keep warm. Stack lefsa on top of each other and keep covered to keep from drying out.