Place cheese and peppercorns into Thermomix bowl and mill for 10 sec/speed 10. Set aside,
Place leek and butter into Thermomix bowl and chop for 3 sec/speed 7. Sauté 5 min/Varoma/speed 1. Add potatoes, and chop few sec/speed 4.
Add water and stock powder and cook 15 min/100°C/speed 2-3 until potatoes are well cooked.
Add milk and cheese mixture and cook for a further 4 min/100°C/speed 2-3. Puree by bringing speed up slowly 30 sec/speed 8. The liquid is extremely hot and may spit as the speed increases, so use caution.