1. Heat oven to 350 degrees F. Coat baking sheets with nonstick cooking spray.Prepare Dough:
2. Stir together flour, baking powder and salt on a piece of waxed paper.
3. Beat together butter, margarine and sugar in a bowl until creamy. Beat in egg, orange rind and vanilla until well-blended. Stir in flour mixture. Shape into disk; wrap in plastic wrap. Refrigerate several hours or overnight.Prepare Filling:
4. Combine apricots, juice and brown sugar in a small saucepan. Cover; simmer until apricots are very soft, 10 minutes. Puree in food processor; if too thick, add more orange juice and puree until well-blended.
5. Divide dough into thirds. Roll each third on lightly-floured surface into 6-inch square. Cut into 9 squares. Spread scant teaspoon filling on each square, from one corner diagonally across to opposite corner. Fold opposite corners over filling and press to seal. Repeat with remaining dough and filling (see Note).
6. Place cookies on baking sheets and bake in 350 degrees F oven 10 to 12 minutes. Cool on racks; sprinkle with confectioner's sugar and serve.