This traditional Finnish casserole is characterized by its long cooking time and a subtle sweetness. It is prepared with a combination of mashed potatoes and wheat flour that is stored in a warm place for hours, allowing the starch to break down and provide the natural sweetness.

The dish is sometimes additionally sweetened and seasoned with nutmeg before it is baked until a golden-brown, crispy crust forms on top. Traditionally associated with Christmastime, this creamy, starchy casserole is usually enjoyed as a side dish.