Whittards has a nice Iced Chocolate receipe as well. It's not too bad actually..
Add 3 tsp hot chocolate powder in a small cup.
Add a touch of hot water and mix into paste
Pour into blender with 3-4 ice cubes.
Add 2 small cups of cold milk (not sure why they say small. I thought a cup was a cup!)
1 tsp of sugar if desired
blend until ice is crushed. Serve in a latte glass with long spoon
Option: top with whipped cream and sprinkles
I never actually thought of doing this with hot chocolate but like I said, it's not too bad!