1.Preheat oven to 200°C (180° fan forced). Line oven tray with baking paper.
2.Cut a 16cm x 24cm (6-inch x 9½-inch) rectangle from one pastry sheet, place on oven tray. Top with tomato, olives, cheese, onion and basil leaves.
3.Cut a 18cm x 24cm (7-inch x 9½-inch) rectangle from remaining pastry sheet; score pastry in a diamond pattern then place on top of filling, press edges to seal. Brush with egg.
4.Bake tart about 20 minutes.