Step 1
Preheat the oven to 400 degrees F (200 degrees C). Line an oven-safe skillet or baking pan with aluminum foil.
Step 2
Poke the potato skin all over with a knife and place on the prepared pan.
Step 3
Roast in the preheated oven until very tender and easily pierced with a knife about 1 hour. Let sit until cool enough to handle but still very warm.
Step 4
Scoop potato flesh out into a bowl. Mash smooth with the back of a spatula until there are no lumps left. You can also use a potato ricer. Add the butter and mix until it disappears. Add the salt sugar and cream; mix until smooth. Cover and refrigerate until chilled about 2 hours.
Step 5
Mix in flour in several additions until the dough is able to be kneaded by hand. Add enough flour to form a soft but not too sticky dough. You need to be able to roll it out fairly thin without it falling apart.
Step 6
Wrap dough with plastic and refrigerate until chilled about 1 hour.
Step 7
Divide dough into 8 portions. Dust each with flour and roll out onto a well-floured kitchen towel to 1/8-inch thick or thinner.
Step 8
Heat a very lightly buttered nonstick pan over medium-high heat. Cook the lefse in the hot pan poking the surface lightly with a fork until golden brown blisters form 2 to 3 minutes per side. Stack on a plate as they're cooked and keep covered with a towel. Serve warm.