What black arts could have stripped this chocolate of its natural hue?

What if H.P. Lovecraft had written copy for a chocolate company?

Peanut Butter Cup

In 1856, a fisherman from a tiny hamlet on the New England coast made a terrible pact with serpentine beasts from beneath the sea, that he might create the most delicious sweet seen upon the Earth since the days of the great Elder Race. Thus was forged the satanic pact between peanut butter and chocolate that resulted in the mutant offspring you see before you!

These are fantastic: I'm both hungry and deeply terrified...