First, wash the potatoes and put them whole in the oven (170° C), for 40 minutes.
In the meantime, vacuum seal the milk and chunks of Grana Padano and put them in the waterbath (75° C) for 15-20 minutes.
After 15 minutes, mix the content with a hand blender, put it through a sieve and mix in the proespuma. We put the mixture in a siphon and mix it through with 2 cream chargers per bottle. Keep it warm.