Slice each piece of pastry in half so you have 4 long rectangles. Place half a sliced apple on one side of each piece of pastry, slanting and overlapping them so they sit as flat as possible. Cut the butter into 4 thin slices and lay one piece over each of the sliced apples. Sprinkle with the cinnamon, brown sugar and a small pinch of salt. Fold the pastry over the apple mixture and press down on the edges with a fork, making sure the two layers are sealed well. Place the turnovers on a baking paper-lined baking tray, brush with the beaten egg and sprinkle generously with the raw sugar. Bake for 20 minutes or until the pastry is a deep golden and beautifully puffed up.