Preheat the oven to 200C/400F/Gas 6.
Place one square of filo pastry onto a non-stick baking sheet, crumple slightly and brush with beaten egg. Place another piece of pastry on top and again brush with egg. Repeat with the remaining pastry and egg.
Place the baking sheet into the oven and bake the pastry for 5-6 minutes, or until golden-brown and crisp.
Sprinkle the top of the pastry with the Taleggio slices and rocket and set aside.
For the rocket pesto, place all the pesto ingredients into a small food processor and blend until smooth.
To serve, place the tart onto a serving plate, drizzle with the rocket pesto and top with a poached egg.