
Cocoa bitters are concentrated aromatic bitters flavoured with cacao, dashed into drinks to season them — essentially the same thing as chocolate bitters.
Dark, roasted cacao up front, with a dry cocoa-husk bitterness and often a faint warmth of vanilla or spice. Almost no sweetness.
A dash or two adds roasted-chocolate depth to a stirred drink — it flatters brown spirits and sweet vermouth, so it's at home in a Manhattan, Old Fashioned or Boulevardier. It brings aroma and a bitter edge, not sweetness, and like any bitters it's dosed sparingly.
Chocolate bitters are effectively interchangeable. A mole-style bitters also works if a little chilli and spice is welcome.
They're made by macerating roasted cacao nibs and warm spices in high-proof spirit, then adding bittering agents for a potent, chocolate-forward tincture. Because it's the nibs, not sweet chocolate, the result is dry and cocoa-bitter, not sweet.