Combine sugar and salt in a medium bowl. Stir to mix completely.
On a working surface such as a large cutting board, pour 1 cup of the sugar/salt mixture. Spread to cover the surface of the board.
Unfold 1 puff pastry sheet, on the layer of sugar/salt mixture. Pour ½ cup of the remaining sugar/salt mixture, covering the puff pastry sheets evenly. With a rolling pin, roll out the puff pastry to 13×13-inches, pressing the sugar into the dough.
Fold the right and left sides of the 13×13 square towards the middle. The edges should meet in the center. Fold them again so that the right and left side meet in the center of the dough. Fold the right side over the left side. You should have 6 layers.
Repeat with a second puff pastry sheet, using the last ½ cup of sugar/salt mixture to pour on the second rolled out pastry sheet. Continue with the process of folding listed above.
Slice the dough into ½ inch slices (in a sawing motion, don’t press down). Arrange each slice cut-side up on the prepared baking sheet.
Bake for 5-7 minutes or until the cookies are golden and caramelized. Carefully turn each cookie with a spatula and bake 3-5 minutes more. Transfer to a cooling rack to cool completely.