Preheat oven to 200°C. Line 2 trays with baking paper and cut each sheet of pastry into 2, one piece slightly wider than the other. Set aside.
Place pecorino and peppercorns into TM bowl and mill 10 sec/speed 10. Remove from bowl and set aside.
Place leek and butter into TM bowl and chop 3 sec/speed 6. Scrape down sides of bowl and sauté 5 min/Varoma/speed 1/MC off.
Add milk, eggs, salt, cornflour, and milled cheese. Cook 8 min/80°C/speed 3. Remove from bowl and cool.
Spread the béchamel evenly on the larger pieces of pastry. Top with soft cheese. Place other piece of pastry on top and pull up bottom piece and fold over, pinching shut. Brush with egg wash. Bake 20-25 minutes or until golden and fragrant.
Serve piping hot with a fresh salad.