Bring the corners of each foil square up and crimp together to seal and form a package around each apple. Do this carefully, as the caramel will still be very hot . Remove from oven. Cool for 15 minutes. Refrigerate for 2 hours to overnight.
Ice water Combine the flour and salt.
Cut the butter into very small cubes and begin working it into the flour with a wooden spatula. Add the cold water in a pool in the center of the mixture and fold the mixture over a few times in the bowl. Dump the dough onto a cool surface, such as marble, and press any loose chunks into the mass. Repeat fold one more time. Wrap in plastic wrap and chill for 30 minutes.