Boil the potatoes. Peel the potatoes while still warm and run them through a potato ricer twice.
Let the potatoes cool in an uncovered bowl in the fridge.
Stir the salt, sugar, melted butter, and cream into the riced potatoes.
Slowly add the flour and knead by hand until you get a good consistency. Don't add more flour than necessary! Roll the dough into a long sausage and divide into about 7 or 8 pieces if using an 18 inch griddle. If using a smaller griddle or frying pan, divide the dough into 10 - 12 pieces.
Roll each piece into a ball and then press into a flat circle, using the edges of your hands to form the dough into a nice circle shape without any cracks. This is important, otherwise you won't get round lefser.
Heat up your griddle on medium/high heat.
Flour your rolling surface and roll the lefse dough into a large circle slightly smaller than your griddle or frying pan. Begin rolling with a smooth rolling pin, then switch to a corrugated rolling pin as the lefse gets thinner. Don't use too much flour, as then the edges can become hard.
Roll the lefse onto your lefse stick and then gently unroll it onto your griddle. After a minute or two check the underside of the lefse for brown spots and then use the lefse stick to flip the lefse and cook on the other side.
Use the lefse stick to remove the lefse from the griddle and place it in a folded damp sheet or tablecloth.
Kling
Mix the softened butter, sugar, and cream together until smooth.
Spread the butter mixture in a very thin layer across the lefse. Fold the edges of the lefse in to make a rectangle (see video). Then cut two triangles from another lefse to cover the empty sections.
Spread another thin layer of the butter sugar mixture across the rectangle. Fold the rectangle in half and then cut into small rectangles to serve.
Store the lefse with kling in an plastic bag in the fridge or freezer.