Hi Pauline, I buy Bourneville cocoa powder and mix it in a plastic container with dextrose in a ratio of 2 parts dextrose to one part cocoa. Premixing avoids the need to mix a paste as it will dissolve readily in both cold and hot milk, and having it ready mixed makes it as easy to use as Milo or Quik. 

Initially, you may find that you need to use more dextrose than I suggest above. My sweet tooth has diminished to the point that the 2:1 ratio is sufficient for me. Generally you will find the cocoa powder in the baking ingredients area of the big supermarkets.

David

I love the label. 

I am still using the original tin I bought of Jarrah chocolate light and toffee with the artifical sweetners in them.  I am starting to find them a bit sweet so will have to make my own.  Thanks for the recipe.  I have a milkshake maker and it makes a refeshing summer drink and so frothy.  Isn't it interesting how our tastes are changing that I am now finding things too sweet.