Peel the apples and cut them into thin slices. Cut the slices into chunks and put them in a large zipper bag. Add the sugar and spices and shake the bag to combine. Put apple mixture in the refrigerator for 4 hours. You will add the tapioca later.
Make the crust. Combine the flour, salt and sugar in a food processor and pulse to combine.
Add cut up butter and pulse until mixture is coarse.
Add water 2 tablespoons at a time, mixing or pulsing, until mixture holds together. Do not keep processing until it forms a ball -- you just want dough that is moist enough to hold together when pinched.
Empty dough onto a large pastry mat and pat it into a large rectangle. It should be moist enough to hold together, though it will crumble slightly. Pat until it holds together, then fold it over on itself and pat to make a block. Wrap in plastic wrap and chill.
Assemble the hand pies, but before doing so add your ground tapioca to the bag of apples and shake it well. Let sit for about 10 minutes more in the refrigerator.
Divide the chunks of dough into 4 3 ounce pieces. Take one piece and roll it into a circle between 6 and 7 inches on a floured surface.
Spoon filling on half of the the circle, then fold over and trim. Save trimmings.
Crimp edges and set on a parchment lined plate. Repeat, creating 4 more hand pies (using trimmings will give you 5 altogether), then put all of the pies in the refrigerator for 1 hour.
When ready to bake, preheat oven to 400 degrees F. Line a large baking sheet with parchment paper (or nonstick foil).
Arrange pies on the baking sheet. Brush with milk and sprinkle with sugar. Bake 25 to 30 minutes or until pies are golden. Let cool slightly before serving.