Pre-heat oven to 190°C; 375°F: Gas 5.
Remove the rind and roughly chop the bacon.
Peel and roughly chop the onion and apple.
Mix the bacon, onion, apple and chopped parsley together seasoning well.
Place into a 600ml (1 pint) pie dish.
Mix the cornflour with a little cider, pour it and the remaining cider over the mixture.
Roll out the pastry, on a floured surface.
Cut a strip long enough to fit around the edge of the pie dish.
Moisten the rim of the dish and press the pastry around the edge of the pie dish.
Moisten the strip of the edge and add the lid of the pie.
Trim excess pastry and crimp the edges together in a fluted pattern.
Decorate with excess pastry if desired, brush with beaten egg.
Bake for 45 minutes or until golden brown and the filling is cooked.