Pre-heat the oven to 200°C. Unroll the pastry sheet. Spread the butternut squash evenly over the top, leaving a little space around the edges, then sprinkle two-thirds of the cheese over.
Fold in half and gently squeeze the edges shut. Roll the pastry very gently (otherwise the squash will escape) until it's about the same size that you had originally.
Cut into 1cm wide strips, twist a few times and place on a non-stick baking tray. Scatter the remaining cheese over the top and bake for 15-18 minutes until golden.
Remove from the oven and allow to cool. Best served warm from the oven but fine the next day too if stored in an airtight container.