I agree with an earlier commenter: a little saline ties the lime and the chocolate flavors together. A little salt helps most daquiris, particularly this one.
Armed with 2 new bottles (white and brown crème de cacao) and Mr H's request for a rum based fruity cocktail I stumbled on this...and we like it very much!
Having just tried this served up with Rhum Barbancourt 8 and Cartron dark as the whole of the creme de cacao, I would opt to serve this instead over a few cubes. Not sweet enough to do with crushed ice... Much more rich, dynamic flavor with El Dorado 8 and Tempus Fugit creme de cacao. Serving suggestion still applies. Either way, could use a drop or two of saline.
Made this with dark creme de cacao only as I have no white, and about half the sugar as we don’t like things too sweet. It makes a lovely dark and slightly bitter chocolate daiquiri.