Sweetening this rich sauce with brown sugar, agave syrup, and vanilla extract cuts back on empty calories and also adds an antioxidant punch.
Combine first 4 ingredients (through coffee granules) in a food processor. Process until finely ground (about 1 minute).
In a small saucepan, stir water and agave syrup together; bring just to a boil over medium-high heat. With the food processor running, add the syrup mixture, then vanilla. Continue processing until sauce is smooth, scraping down sides as needed. Transfer to a container and refrigerate until chilled (at least 2 hours). Stir before serving over fruit, ice cream, or banana bread.