Preheat the oven to 400°F. Add the demerara, granulated sugar and pumpkin spice to a medium bowl. Mix to combine.
Add 1/3 of the sugar mixture to a clean dry surface and spread to about 9" X 11".
Add the thawed puff pastry on top of the sugar and roll to a 9" X 11" rectangle that is 1/4" thick.
Roll one side of the long end inward to the centre. Repeat on the other side so that the rolls meet evenly in the centre.
Sprinkle the top of the rolled pastry with 1/2 of th coarse sugar and gently tap to help the sugar stick. Carefully roll the dough over and repeat on the other side.
Roll the dough back onto the flat end and using a sharp knife cut the dough into 12 equal slices. Place the cookies on a parchment-line baking sheet and bake for 10 minutes or until the pastry appears flaky and golden. Remove from the oven and let cool completely before serving.
Notes
Storage:Store these puff pastry cookies in an airtight container on the counter once completely cooled for 3-4 days. I do not recommend freezing these cookies as they will lose their flaky texture.If they begin to get soft you can always pop them back in the oven at 375°F for 5-10 minutes to crisp them up.