Prepare pie dough.
Lightly dust work surface with flour. Roll out larger piece of dough to a circle 1/4-inch thick and about 13-inches in diameter. Transfer dough to 9-inch pie plate. Press the dough to the sides and bottom of pie plate. Allow excess dough to hangover plate. Cover with plastic wrap and keep chilled in the fridge.
Roll out smaller piece of dough to a circle 1/4-inch thick and about 11-inches in diameter. Cover with plastic wrap and leave at room temperature while you prepare apples.
Preheat oven to 425 degrees F.
Apple Filling: Whisk together brown sugar, flour, cinnamon and salt. Set aside.
Wash, peel, and core apples. Slice apples to about 1/4-inch thick. Place sliced apples in a large bowl. Add lemon juice and toss to distribute. Add brown sugar mixture and fold to coat apple slices.
Place apples in dough-lined pie plate, making a mound in the center. Distribute cubed butter over the apples.
Place remaining rolled dough over apples. Cut vents in the center of the dough to allow steam to escape during baking.
Trim excess dough, leaving about a 1-inch overhang. Fold overhang into the pie and flute the edges with a fork, or crimp with your fingers.
To make egg wash: whisk together egg and milk. Lightly brush the top of the pie with egg wash. Sprinkle with topping.
To making topping: whisk together turbinado sugar and ground cinnamon. Sprinkle over egg washed pie.
Plate pie plate on a baking sheet. Bake for 15 minutes. Reduce oven temperature to 350 degrees F. Bake for another 40-45 minutes, rotating pie halfway through baking. Bake until top of pie is golden brown and apples are tender. Test to see if apples are done by piercing a knife through the vents. Let pie cool to room temperature on a wire rack. Serve at room temperature.