Is there a way to make peanut butter buttercream white?
I have never used them personally, but there are peanut butter extracts and oils out there that you could try adding to your buttercream. If the extract/oil adds a bit of brown color, you could always add a bit of white food coloring to help counteract it.
Oops! In case this isn't obvious, I meant use the oil extract with a white vanilla buttercream instead of trying to make a white buttercream made with real peanut butter.