Cut the pastry to four pieces, and work with one at a time (put the rest back to the fridge). On a well-floured surface, roll the pastry to a 0.5 cm thick disc and cover that with 2-3 tablespoons of jam (leaving a 1 cm edge around) and sprinkle 1/4th of the filling over. Press a bit with your hands and use a pizza slicer to cut into 8 slices.