 The Berliner is more common than U.S.-style doughnut, and sold in most supermarkets and bakeries alongside "smultring" doughnuts.In Poland and parts of the U.S. with a large Polish community, like Chicago and Detroit, the round, jam-filled doughnuts eaten especially—though not exclusively—during the Carnival are called pączki ().Pączki have been known in Poland at least since the Middle Ages.