Once the pastry has chilled, take one half of it out of the fridge.
Dust a smooth surface and rolling pin with flour.
Roll out the pastry to around 1/4 cm (1/8") thick (ideally at least 20cm x 30cm / 8" x 12").
Cut out 4 long rectangles 7cm wide x 20cm long (3" x 8") each (you’re going to be folding them over). Lay them on a baking tray covered in baking paper.
Repeat with the 2nd batch of pastry.
Loosen up the jam (which should be completely cold before you use it) by stirring it vigorously.
Spoon 1 tablespoon of jam into the centre of the bottom half of each of the the pastry rectangles, leaving at least a 1cm border around the edge.
Fold the top half over and seal the edges by pressing down until firmly sealed.
Cover with cling film and then put back in the fridge for 30 minutes to chill.