Knead all the ingredients (except preserves) mixing them together thoroughly. Cover the dough with a cloth and put in a cool place to set. Divide dough in half. Crumble 1/2 of the dough into a prepared baking sheet, spoon preserves over the crumbs. Crumble the other half of the dough on top of the preserves. Bake in a hot oven 45-50 minutes. When done, sprinkle the square with powdered sugar.
Recipe taken from: Lithuanian Cookery, Izabele Sinkeviciute, 1980