Place cheese and peppercorns into the Thermomix bowl and mill 10 sec/speed 10. Set aside.
Place leek and butter into the Thermomix bowl and chop 3 sec/speed 7. Sauté 5 min/Varoma/speed 1. Add potatoes and chop 5 sec/speed 5.
Add stock and cook 15 min/100/speed 3 until potatoes are well cooked.
Add milk and cheese mixture and cook for a further 4 min/100/speed 3. Puree by bring speed up slowly 30 sec/speed 8. The liquid is extremely hot and may spit as the speed increases, so use caution.
Serve soup out into bowls and top with shaved Truffle.