Hardangerlefse is a variety of Lefse that gets risen, either with yeast, or with a chemical leavener.
If a chemical leavener is used, it is commonly baking soda activated by either soured milk or buttermilk
Typical ingredients for the dough are flour, sugar, buttermilk, butter, and baking soda. Some richer recipes add a syrup (such as white syrup or golden syrup) and eggs.
The ingredients are mixed, allowed to rest, then rolled out thinly and cooked as per regular Lefse (on a dry, ungreased, hot griddle.)
As they come off the griddle, they are stacked with sheets of waxed or greaseproof paper in between.
To serve, lay one out, butter it, dust with cinnamon sugar, top with a second one treated the same, and cut into triangular, pie-shaped slices.