Combine flour and baking powder. Beat butter, cream cheese and granulated sugar in large bowl with mixer until light and fluffy. Gradually beat in flour mixture.
Divide dough into thirds; shape each into ball. Flatten each ball slightly; wrap separately in plastic wrap. Refrigerate 1 hour.
Heat oven to 350°F. Roll out 1 ball of dough into 1/8-inch thickness on lightly floured surface. Cut into 2-1/2-inch squares, rerolling trimmings as necessary. Spoon about 1/2 tsp. pastry filling onto center of each square. Use finger tip to lightly moisten 2 opposite corners of each dough square with water, then overlap corners in center and press together to seal. Place, filling sides up and 1 inch apart, on baking sheet. Repeat with remaining dough.
Bake 13 to 15 min. or until lightly browned. Cool on baking sheets 3 min. Remove to wire racks; cool completely.
Sprinkle lightly with powdered sugar before serving.