https://en.wikipedia.org/wiki/Berchtesgaden

Berchtesgaden, Upper Bavaria (Achental), earlier Perchterscadmen, Perhtersgadem, Berchirchsgadem, Berchtoldesgadem; the word underwent a Latin distortion of Old High German parach, Romance bareca 'hay shed'. After the basic meaning was forgotten, a variant word of Old High German gadem 'room, one-room hut' was added, implying the same meaning: 'hay shed'. Cf. Old High German muosgadem 'spice room'.

There was a folk etymology that supported a derivation based on the legendary figure of Frau Perchta (Berchta), a woman (Holle < Holda 'well disposed, dear') with good and bad changing features, who was venerated on Perchtertag (Shrovetide) and was sworn to during the Perchta procession.

german wiki also mentiones a proprietary church or cloister called berthercatmen.

interdasting, innit?