First mix the egg, flour, sour cream and 250g butter together. Then you roll out the dough and put it on a baking sheet (don`t forget baking paper). You distribute the rest of the butter on the dough and then you can sprinkle sugar on the dough as you like. Bake the casseroles at 200 ° C for approx. 25 minutes (until everything is lightly brown). Cut into squares before cooling.