Put cocoa powder in a sauce pot. In a separate pot, boil water with salt. After water reaches boiling pour over cocoa powder and whisk together. Again bring to a boil making sure not to scald the cocoa. Whisk in agave nectar and milk and heat. (DO NOT BOIL at this point). Finally remove from burner and add vanilla extract.
If desired, add heavy cream or whipped cream before serving. Enjoy! Serves 4.