To make the choux pastry, combine water, butter and sugar in a sauce pan and bring to the boil. Add the flour and stir for a few minutes on a lowish heat until the roux becomes shiny and pulls away from the sides of the pan.

If you have a food mixer, dump the hot mixture into it and mix with the paddle attachment until it stops steaming, if you don't have a mixer just cover with cling film with a few puncture holes to allow the steam to escape until it has cooled to room temperature. Now start adding the eggs, 1 by 1 and turn off the mixer when you add (in case you drop the whole egg inc shell) mix each egg until combined until all eggs are incorporated.

Now pipe the choux pastry with either a piping nozzle or if using a disposable bag just make a clean cut around 1cm in diameter. You decide what size to pipe but the standard would be around 4 inches long and 1 inch thickness (approx) Keep a steady squeeze and a slow deliberate movement (practice makes perfect) Leave room for each eclair to expand when baking. I'm using a silicone baking mat here but you can use baking parchment, tip make a few dots of the pastry under the paper first to secure.

Now with a wet finger even out your pre-baked eclairs (this also creates a little steam in the oven which aides the rise. 200c oven for about 20-25 minutes, after 15 minutes you can see these eclairs are not quite done, they will collapse the third image are perfect. leave to cool on a wire rack.

Break up the chocolate into a glass or stainless steel bowl, sit over simmering water DO NOT ALLOW THE WATER TO TOUCH THE BOW! When the chocolate has melted add in the icing sugar and cocoa

Stir in the icing sugar and cocoa as best as you can and then start adding hot water with a ladle from the simmering pan, do this about 1 tbsp at a time and work until you have achieved a beautiful glossy THICK chocolate sauce. Keep this mixture warm while you fill your eclairs.

Combine cream, icing sugar and vanilla in a bowl and whisk to firm peak, using a piping bag with a thin nozzle pipe cream into pastry shells until you see it ooze out, you can make a hole with a knife at each end of the pastry to make this easier.

Dunk the cream filled pastry into the still warm chocolate mix and hold for a few seconds, allow some excess chocolate to drip off and leave chocolate side up on a rack or tray. refrigerate fully before serving

These screen shot images are taking from my Youtube channel why not watch the video? https://www.youtube.com/watch?v=TIywaOWPfI4&t=88s