In a food processor, add your flour, salt, and cube in your butter. Pulse a few times, until your butter chunks are about the size of a pea. Pour in half of your water, and pulse. Add remaining water and pulse again, just until your dough starts to pull together.
Take a little more flour and sprinkle it on the dough. Pat it together until it forms a soft ball. Divide your dough in half. Sprinkle your work surface lightly with flour. Roll out half of your dough. Place your rolled crust into a greased ramekin. Repeat the process once more.
Next take your washed apple, and remove the core. Do not remove the apple's peel. Place the apple on top of your crust in the ramekin.
In a small mixing bowl, combine brown sugar, cinnamon, flour, and granulated sugar. Pour half of the mix, into the center of one apple (where the core was). Repeat with the remaining apple. Divide the butter in half and add to the center of each apple core hole.
Take your crust, and pull it up from the bottom, to completely cover your apple. Pat so that it stays in place if needed.
Brush the top with milk and sprinkle with sugar. Bake at 375°F for 20 minutes, then check on it. To tell if your apple is baked, try inserting a sharp knife in the top. If you feel resistance, continue baking. Once fully baked, remove from the oven, serve and enjoy!