Sorry for the somewhat weird title, potetkake doesn´t (I discovered) have a really good English translation. Lompe is another Norwegian name for this funny looking, traditional, yet scrumptious whatchamacallit. Since another Norwegian synonym probably doesn´t help you much, I am just gonna call it potetkake for the rest of the post, ok?
And I will do my best to explain to you what it is and I will present one very traditional way to use it, and one untraditional (at least in my region!). Both delicious!