"Exports of chocolate provide you with Crates of Coin from your Home City. You get 1 Crate per 2 minutes of game length."—In-game description
Aztec Chocolate Recipes is a technology in the vanilla Age of Empires III that can be researched at a Trading Post built on an Aztec settlement. Once researched, it ships 100 coin for every 2 minutes the game have passed, up to 30 minutes (for a total of 1,500 coin).