If using puff pastry sheets, top the first sheet with sugar and superimpose with the second sheet. Roll out into a 20 inch (50cm) rectangle and fold in 3 like a business letter (single turn); chill for an hour or more to rest. If using puff pastry from scratch, add sugar to its last single turn (6th); chill to rest. (Watch puff pastry video). Roll out pastry into a 25 inch (65cm) length adding sugar as you go. Trim off edges and fold each side in 2 leaving a small space in the center and fold. The finished palmier slab should measure 9.5x4''/ 24x10cm. Wrap up and chill overnight. Sugar will begin to melt.. no worries. Cut palmier slab into 16 x 1/2''/1.25cm thick portions – chill prior baking to rest.
Preheat oven to 350ºF/180ºC. Arrange cookies in 2 large baking trays (8 per tray) and bake one tray at the time for 20 minutes. Flip palmiers carefully and bake for an additional 10 minutes or until caramelization is achieved. Palmiers should remain crispy for a couple of days. Enjoy!