Mix plain flour and salt, grate the butter and mix them together, gradually pour ice water until the dough becomes elastic when it pressed. Divide it into two and wrap it with cling wrap. Rest them overnight.

Pre-heat the oven 200° C.

Wipe the tray with lightly with margarine, roll the first dough, place it in the round tray neatly, pour the apple mixture into the tray and pat it down.

Roll the second dough and cut it long rectangle with pizza cutter or knife. Put it on top of the apple mixture, cut the extra dough around the edge, and pinch the edge together to make it looks charming.

Crack an egg and mix it well with sugar, use a cooking brush to wash the top of the pie.

Bake the pie into the pre-heated oven for 30-45 mins in 200° C. You will know it when it's done when you see the juice are bubbling through the vents on top of the pie, otherwise it needs more time to bake.