Heat the oven to 200C/fan 180C/gas 6. Roll the puff pastry to 1/2cm thickness. Sprinkle the grated parmesan, a few pinches of cayenne pepper,rocksalt and some black pepper over, then gently press into the pastry. Cut into 21/2cm-wide strips about 15cm long. Twist each strip a couple of times, lay out on a baking sheet and cook for 20-25 minutes until puffed and golden.