An Old Aztec Cocktail combines rye, sugar, water, orange peel, orange bitters and chocolate bitters. It is essentially an old fashioned recipe and prepared in the glass as such. I got my recipe from Abby at No Fail Recipe. I forgot to take a photo of mine so the one above is from the site. Apparently Abby uses more ice than my two cubes and she garnishes with a cherry which I did not - nice idea, though.
I tried this drink mostly as a test of the Aztec Chocolate bitters. Frankly, there isn't much in the way of chocolate flavor, though the aroma certainly bloomed nicely as soon as it hit the glass. My wife felt the drink does have a sort of chocolate chewiness - not sure what she means but she's the supertaster so I'll trust her. Otherwise, it's a perfectly nice drink.