HEAT oven to 350 degrees F. Mix flour and salt in a medium bowl. Cut shortening into flour mixture with pastry blender. Cut in cottage cheese and vanilla until a firm dough is formed.
SPRINKLE counter with powdered sugar. Roll out dough to 1/8-inch thickness. Cut into 2-inch squares. Fill with 1/2 teaspoon preserves. Overlap opposite corners; seal tightly. Place 2 inches apart on ungreased baking sheets.
BAKE 14 to 16 minutes or until light golden brown. Cool 2 minutes. Remove to wire rack to cool completely. Arrange on serving platter; sprinkle with powdered sugar, if desired.