There are many roads to Rome and to chocolate syrup.
The simplest and best is just to mix equal volumes of honey and excellent cocoa. You might also want to use up to twice as much cocoa as honey, depending on your desired sweetness—remember that honey is about 50% sweeter than sugar!
I like Askinosie’s or Dagoba cocoa.
Stir continuously over medium heat–takes about 5 minutes.
Considering the fact that honey never goes bad, even when 5000 years old, this syrup will keep indefinitely in the fridge. It will become semi-firm but dissolves easily into hot coffee for great mocha or into hot milk for instant hot chocolate. It will need to be reheated to put over other dishes.