Cream the butter and cream cheese; beat until light and fluffy. Add flour, mixing well. Roll out the dough onto a lightly floured surface to 1/8 inch thickness; cut into rounds with a 2-inch cookie cutter. Place on lightly greased cookie sheets. Spoon 1/4 teaspoon jam on each cookie; fold in opposite sides, slightly overlapping edges. Bake at 375ºF. for 15 minutes. Remove from cookie sheets, and sprinkle with powdered sugar. Yield about 2 dozen.