Preheat oven to 400 degrees F.
To prepare the piecrust, combine the flour and salt in a large mixing bowl. Cut in the shortening with your fingers or a pastry cutter, until the pieces are the size of small peas. Sprinkle 6 tablespoons water over the flour, and gently toss with a fork. Push the flour to the sides of the bowl, add the remaining cold water, and mix until all is moistened and combined. Divide the dough in half, and form each half into balls. Wrap each ball in plastic wrap and refrigerate.
In a large mixing bowl toss the apples with lemon juice. Combine the sugar, flour, brown sugar, cinnamon, and nutmeg. Add the apples and toss until completely coated. Set mixture aside.
On a lightly floured surface, roll out one ball into a 12-inch circle, and place into a 9-inch pie plate.
Transfer the apple mixture into the pastry lined pie plate. Cut the butter into small cubes and add to the apple mixture. For the top crust, roll out remaining dough, place on top, and seal and flute the edge. Cut slits on top crust to allow steam to escape.
To make the egg wash, crack egg in a small bowl, add a pinch of salt, whisk, and brush on top of the pie. Cover pie with foil to prevent over browning, and bake for 25 minutes. Remove foil and bake for an additional 25 minutes until crust is golden and apples are tender.
Serve warm with ice cream or just plain.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.