Peel core and slice approximately 6 apples. I like to keep my apple slices pretty big so that they still have a bite to them. If you prefer a softer filling, feel free to cut them smaller.
Whisk egg in a small bowl and set aside.
Roll pastry into a circular shape. Use your pie dish as a guide, ensuring pastry is wider in diameter.
Place pastry into pie dish, pushing it down so that it fills into the corners.
Prick the bottom several times with a fork.
In a bowl, toss the apples with the lemon juice, cornstarch sugar and cinnamon.
Fill the pie with the apple mixture.
Then, roll out the second piece of pastry dough for the top.
Using a pastry brush, put egg wash all around the perimeter of the pastry (this will help seal it when the top piece goes on).
Place the top piece of the pie dough on top. Seal the edges with a knife or fork by pushing down. You can also crimp them with your thumb and forefinger. Cut off any excess with a sharp knife.
Brush entire pie with eggwash.
Put three slits in the middle of the pie to help steam escape while baking.
Place in the oven at 425 degrees F. After 15 minutes, reduce heat to 400F and bake for another 20 minutes or until the crust is golden brown.
Keep an eye on the edges of the pastry. When they start to get golden, place some foil around the edges to stop them from burning.
When the pie come out of the oven, let it rest for 30 minutes before eating it. This allows it to firm up.
Serve with sprinkled sugar on top and freshly whipped cream.