Preheat the oven to 350°F. Line two baking trays with parchment paper.
Lay out the sheet of puff pastry on a lightly floured work surface. Sprinkle half of the cheese all over the top and, using a rolling pin, lightly roll the cheese into the pastry. You should apply enough pressure so that the cheese is pushed into the pastry, but not so much that you change the size of the rectangle. Carefully flip the pastry over and repeat with the remaining parmesan cheese.
Cut the pastry crosswise into long thin strips. Lay the strips side by side on the prepared baking trays. Bake for about 10-12 minutes, or until the pastry is nice and golden. Transfer to a platter to serve.
For warm breadsticks and a wonderful aroma in your house when guests arrive, prepare the breadsticks until just before you bake them. Put them on the baking tray and keep in the fridge until ready to bake.