Notes: This works best if everything is cold (if you make fresh coffee, mix it with the milk and let it sit in the fridge for 1/2 hour
If it is not frothy, add more milk, or even just some more milk powder
The froth gradually turns to liquid at the bottom of the glass, so you will find that you can sit and drink this for about 1/2 hour, with more iced coffee continually appearing at the bottom