The Fat Jewish -- Spencer Pratt Shall Deliver Me From My Demons

Pizza can't solve all problems, not even for The Fat Jewish ... because he's turning to Spencer Pratt for spiritual guidance. No, you read that correctly.

The Instagram comedy curator and pizza fanatic arrived in L.A. Tuesday for a session with his new shaman and former 'Hills' star -- something our photog found hard to believe ... so he hopped the shuttle bus with FJ to get the story.

As we first reported, Pratt is shooting a new reality series, so it's most likely a stunt for the show, but still entertaining to watch.

And if Pratt's crap doesn't work ... Fat Jewish's vintage GWAR shirt should scare off plenty of demons. Just sayin'.