Sweetened potato casserole (finnish imelletty perunalaatikko) is a traditional finnish dish from päijät-häme, eaten elsewhere in finland at christmastime. it is prepared by letting puréed potatoes, mixed with wheat flour, stand at a temperature of around 50°c (122°f). the amylase in the flour will start to break down the potato's starches to shorter carbohydrate chains, that is sugars. the temperature cannot exceed 75°c (167°f); otherwise, the amylase molecules will break down. through this process, the dish gets its distinct sweet flavour; nowadays, however, dark syrup (finnish tumma siirappi) can be added to give it sweetness. dark syrup is made from sugarcane and it's the most common t...

Source: Wikipedia