Pre-heat oven to 425°F.
In a large bowl, mix together the apples, cider, lemon juice and vanilla.
In another bowl, whisk together the dry ingredients.
Stir the dry ingredients into the apples to coat them evenly.
Roll one piece of the pie crust discs to about 13 inches, and then place into a 9-inch pie plate.
Use a slotted spoon to transfer the apples into the pie dish. Sprinkle 2 to 3 tbsp of the liquid over the apples.
Roll out the other pie crust, and lay it atop the pie.
Seal and crimp the edges.
Add the egg to the milk, and gently mix.
Brush the top with milk/egg bath and sprinkle with sugar.
Cut four slashes in the middle of the crust to vent steam.
Bake the pie for 15 minutes.
Reduce heat to 375 F, and bake for an additional 45 minutes.
Let completely cool on baking rack. At least two hours.