Peel and cut potatoes. In a large saucepan cook, covered, in lightly salted boiling water for 20-25 minutes or till tender, drain. Squeeze potatoes through ricer or mash. You should have 4 cups mashed potatoes. Cover and chill. Add flour, butter, cream and salt to chilled potatoes. Beat with an electric mixer on medium speed until mixture is combined. Heat griddle to medium. Roll small portion of dough into a circle that is thin. Roll one more time with "Lefse"roller" if desired. Use a spatula or "Lefse stick" to transfer dough to griddle. Heat on griddle, flipping once so that both sides are lightly browned (about 1 to 2 minutes total). Let cool. May freeze between layers of waxed paper. To eat, spread with butter and sugar and roll up.