Preheat oven to 200C or 180C for a fan and line 2 baking trays with non-stick baking paper.
Combine apples, sultanas, brown sugar and cinnamon in a bowl. Cut the pastry into four equal pieces. Put about 2tbsp of mixture onto each square of pastry and fold over. Press the edges down witha fork and brush the egg on the top. Place apple turnovers on a tray.
Use a fork to prick a few holes in the top of the pastry. Bake for 15-20 minutes, until golden brown. Dust with icing sugar and serve warm at room temperature.