
Dark-veined white (Pieris bryoniae wolfensbergeri)
The German name “Bergweißling” translates to “Mountain White”, hinting at the fact that it is typically found in the Alps. A considerable number of subspecies are listed,
For this particular subspecies, Wikipedia says:
Pieris bryoniae wolfsbergeri Eitschberger, 1983 Type locality: Italia, Piemonte, Termi di Valdieri, S. Giovanni, 1500 m.
And indeed, this one is from Piemont.

"Pieris bryoniae", the dark-veined white or mountain green-veined white, is a Palearctic butterfly of the family Pieridae. It has variously been considered to be a full species, a subspecies of "Pieris napi" or a superspecies complex.