Place the warm, freshly riced potatoes into a large mixing bowl. Add the softened butter, heavy cream, salt, and sugar, stirring until completely smooth and well combined.

Cover the potato mixture and chill in the refrigerator until completely cold, which takes about 30 minutes. The mixture must be cold so it doesn't absorb too much flour later.

Once the potato mixture is cold, gently knead in the all-purpose flour until a soft, pliable dough forms. Be careful not to overmix, as too much kneading can make the final lefse tough.

Divide the dough into 8 equal portions and roll each into a smooth ball. Keep the dough balls covered with a clean, slightly damp kitchen towel to prevent them from drying out.

Heat a large cast-iron skillet or a traditional lefse griddle over medium-high heat. Generously flour a clean work surface and your rolling pin.

Working with one dough ball at a time, roll it out as thin as possible, aiming for an 8 to 10-inch circle. Use a long, thin spatula to carefully lift and transfer the delicate dough to the hot skillet.

Cook the lefse for 1 to 2 minutes until light golden brown spots begin to appear on the bottom. Carefully flip the flatbread and cook for an additional 1 minute on the other side.

Transfer the cooked lefse to a plate and immediately cover with a clean kitchen towel to trap the steam and keep them soft. Serve warm, spread with butter, and rolled up tightly!