Preheat oven to 200°C (180°C fan-forced). Line a large oven tray with baking paper. Join pastry sheets, overlapping them by 1cm and pressing together to join. Place pastry over the baking paper.
Spray a medium sized frying pan with oil. Place spinach in the frying pan and sauté over a medium heat for 1-2 minutes, or until just wilted. Transfer to a colander and squeeze out excess moisture. Spread spinach over pastry, leaving a 3cm border around the edge. Sprinkle feta over top.
Brush pastry edge with a small amount of water and roll up loosely. Cut into 6 equal rounds. Arrange the rounds with the cut-side up on the baking tray. Bake for 15-20 minutes or until the pastry is crisp and golden.
Tip: You could replace fresh spinach with a packet of frozen spinach, make sure it is well drained.