Preheat the oven to 450 degrees F.

In a small bowl mix together the sugar and kosher salt.

Lay down a baking mat or parchment paper. Pour 1 cup of the sugar mixture onto surface and spread evenly in about a 10×10 inch area.

Unfold one of the puff pastry sheets on top of the sugar and pour 1/2 cup of the sugar mixture on top, spreading it evenly on the puff pastry.

With a rolling pin, roll the dough until it’s about a 13×13 inch square and the sugar is pressed into the puff pastry on top and bottom.

Fold the sides of the square towards the center so they go halfway to the middle. Fold them again so the two folds meet exactly at the middle of the dough. Then fold 1 half over the other half as though closing a book.

Slice the dough into 1/2 inch slices and place the slices, cut side up, on baking sheets lined with parchment paper.

Place the second sheet of pastry on the sugared board, sprinkle with the remaining 1/2 cup of sugar mixture, and repeat same process of folding and placing on a second baking sheet with parchment paper.

Bake the cookies for 6 minutes until caramelized and brown on the bottom, then flip them with a spatula and bake another 3 to 5 minutes, until caramelized on the other side. Transfer to a baking rack to cool.