In the food processor, cream the butter with the sugar and salt.
Add the cottage cheese and vanilla extract.
Pulse for 2 minutes or until the mixture has the consistency of whipped cheese. Add the flour and pulse until a ball forms.
Wrap the dough in plastic wrap and refrigerate for at least 3 hours.

Preheat the oven to 400 F (200 C).
Roll out the dough to a thickness of 1/8″ (0.3 cm), on a floured work surface.
Cut out 2″ (5 cm) squares from the dough.
Place a little jam in the center of each square.
Fold the opposite corners to form a triangle.
Seal the edges and make a small hole, with the tip of a knife, on the top of each triangle, so that the steam can escape.
Bake on a cookie sheet lined with a silpat for 10 to 12 minutes.
Let cool on a rack and sprinkle with powdered sugar.