Preheat oven to 400°F
Make sure puff pastry is thawed and ready. Cut into squares about 2-3 inches wide.
Dice one half of an apple into very small cubes. I like it tart, so I used granny smith. But use whatever you like!
In a small bowl, combine apple cubes, brown sugar, cinnamon, nutmeg, and all spice and mix around until coated.
Over medium heat, heat apples in a small saute pan. Pour in apple cider. Bring to a boil. Let apple simmer in the apple cider until it reduces to a gel. About 5-6 minutes.
Remove from heat. Spoon apple mixture into the center of a puff pastry square. I was able to comfortably fit about 2 teaspoons.
Fold over corner to corner and crimp the edges with a fork or a pastry crimper.
Spray a baking sheet with non stick spray. Use an elevated baking/cooling rack if you have one.
Bake at 400°F for 15 minutes. AFter 15 minutes, brush each pastry with melted butter and sprinkle cinnamon sugar generously all over (I only did one side).
Return to over and bake for 5 minutes.
Remove from oven. If the pastries have opened, just gently push them back closed. As they cool, they'll retain their shape and the contents won't leak out.
Let cool for a few minutes before you dig in!