Preheat oven to 375℉ (190℃).
Mix the butter and cream cheese with a mixer or in a food processor taking care not to overprocess.
Add the flour and mix just to combine.
Chill dough 30 minutes.
Roll out the dough very thin on a floured board or pastry cloth.
Cut into 2-inch rounds with a cookie cutter.
Dot the center of each round with ¼ teaspoon of jam or jelly.
Fold 2 opposite edges to the center and press firmly together.
Transfer the pastries to wax paper generously dusted with confectioners' sugar and sift more of the sugar over the kolochy while they are still hot.