Brush each sheet of pastry with water, then sprinkle with caster sugar.
Pair pastry sheets, sugar side in. Roll pastry lightly to increase its size by 20 per cent and to seal. Line a 22cm pie dish with one rolled pastry pair. Sprinkle 1cm of breadcrumbs over the base.
Peel and core apples 7 apples. Cut into 2mm-thick slices and put into a large bowl. Combine the apples, brown sugar, cinnamon, nutmeg and allspice and then layer into the pastry shell. Top with the pieces of butter.
Lay the second pastry pair over the top. Crimp the edges to seal and remove any excess pastry. Brush the top of the apple pie with beaten egg, then sprinkle all over with brown sugar. Cut a small slot or cross into the top of the pie.
Bake pie for 40-45 minutes or when pastry turns golden. Remove and place on wire rack for 20 minutes before serving with ice cream or thickened cream.