Preheat oven to 200°C. Line 2 trays with baking paper and cut each rolled sheet of pastry into 2, one piece slightly wider than the other. Set aside.
Place parmesan 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 completely.
Spread the mixture evenly on the larger pieces of pastry. Top with soft cheese slices. Place other piece of pastry on top and pull up bottom piece and fold over, pinching shut. Score the top of the pastries if desired, being careful not to cut right through the pastry layer. Brush with egg wash and sprinkle with seeds. Bake 20-25 minutes or until golden and fragrant.
Serve hot with a salad or not!