Measure out the instant coffee, granulated sweetener and then add the hot water, then the cold water.
Stir the mixture with a spoon. After a few seconds, there were a few coffee granules present still - but I didn't worry about those.
Once cooled I blitzed it in my Nutribullet for a few seconds. You shouldn't use the Nutribullet with hot liquid as the steam build up can be dangerous. I may have almost sliced my face open once by ignoring this!
Add the cold water and the ice. Then blitz in the Nutribullet.
Get a glass and drizzle a little Monin chocolate mint syrup around the edge. You could use any flavour syrup that you like and there are LOTS out there!