In a skillet over medium heat, melt the butter. To the skillet add chopped apples, brown sugar, cinnamon, and salt. Sauté the apples until most of the liquid has evaporated and the sauce has thickened; about 10 minutes. Transfer to a bowl and chill for 30 minutes or until cool.

Preheat the oven to 425 degrees F and line a baking sheet with parchment paper.

On a lightly floured surface, roll each thawed puff pastry sheet into the same size rectangle so that they match. Then cut each sheet into 6 equal pieces. You will have 12 rectangles of the same size.

If you would like to decorate the top pastry, using a small biscuit cutter or with a pairing knife, cut out a shape in 6 of the rectangles.

Into the center of 6 pastry rectangles (that do not have a shape cut out), place 2 to 3 tablespoons of the cooled apple filling, leaving a 1-inch border around. Brush a small amount of water around the border (this will help seal the pastry) and top with the remaining pastry rectangles. Seal the edges of each hand pie with a fork and then place on the prepared baking sheet.

Brush the tops lightly with water, sprinkle with cinnamon sugar, and bake for 15 minutes or until golden brown. Let cool for 10 minutes before serving warm.