Sweetened potato casserole (Finnish imelletty perunalaatikko) is a traditional Finnish dish from Päijät-Häme.
Puréed potatoes are mixed with wheat flour and allowed to stand at a temperature of around 50ðC (122ðF). The amylase in the flour breaks down the potato's starches into shorter carbohydrate chains, i.e. sugars. The temperature cannot exceed 75ðC (167ðF); otherwise, the amylase molecules will break down. Through this process, the dish gets its distinct sweet flavour; nowadays, however, it can be sweetened with dark syrup (). Dark syrup is made from sugarcane and it is the most common type of syrup in Finland. It has a similar taste to molasses, but is sweeter.
The potatoes, now with a batter-like texture, are mixed with milk and baked for several hours until thickened and caramelized on top.