Old-fashioned Chocolate malt

I have a friend who told me that when her mother or father would make her a chocolate malt as a youngster, they would put a raw egg in it before mixing it up. I never heard of this before and never saw any recipes with a raw egg in it. Anyone have a clue if this is something that used to be done or if this might just be this particular family’s own recipe? Thanks so much!

a little late -

are you sure it was an egg? could have been egg malt powder