Preheat oven to 350ºF. Line cookie sheet with parchment paper.
On floured surface, roll one dough disk 1/4-in. thick (leave remaining disk in refrigerator until ready to use). Cut dough with floured 3-in. round cutter. Gather scraps and chill at least 30 minutes before rerolling.
Place cookies 1 in. apart on prepared pan. Spoon 1 teaspoon jam in center of each. Fold one side of dough circle over filling. Brush remaining side lightly with water; fold over and press lightly to seal.
Bake 12-15 minutes or until pale golden brown on bottom. Remove to cooling grid; cool completely. If desired, sprinkle with confectioners' sugar.