Bring water and milk just to a boil. Add potato flakes and stir briefly. When liquid absorbed, stir again. Measure out 3 cups slightly packed into mixing bowl along with salt and sugar. Chill mixture well. Cut in butter using pastry blender. Cut in the flour then blend in cream or milk. Turn out, knead briefly, divide in half and shape into three logs (about 12 oz each). Divide each log into 6 equal pieces, about 2 oz each. Heat griddle to 400 degrees. With rolling pin, roll to 1/8 inch thick or less (thinner the better) adding plenty of flour as you roll. Cook on griddle until lefsa starts to bubble and golden spots appear. Roll next Lefsa while cooking. Turn and cook other side. Cool on rack. Fold in half, wrap in paper towels, seal in zip lock freezer bags and refrigerate or freeze.