Preheat the oven to 210'C.
Cut the butter into small pieces. Sift the flour.
Place the water, salt and butter in a saucepan and bring to the boil. Once boiling, remove from the heat and mix in the sifted flour. Return to the heat and mix until the mixture no longer sticks to the bottom of the pan. Transfer to a food processor and beat in the eggs one by one. The mixture should be shiny and smooth and have a dropping consistency. You may not need to add the whole of the third egg.
Place the mixture into a piping bag and pipe small profiteroles on to a baking tray. Bake for 10 to 15 minutes.
Reduce the oven temperature to 160'C and cook the profiteroles for a further 10 minutes to dry them thoroughly and make sure they hold their shape.
Cut the vanilla pod in half lengthways and scrape out the seeds. Whisk the cream with the icing sugar and vanilla to soft peaks. Fill a piping bag with this mixture.
Pierce a small hole in the base of each profiterole and fill with the chantilly cream.
Place the double cream and the milk in a saucepan and bring to the boil. Break the chocolate into small pieces and then pour the cream/milk over the top. Whisk until the chocolate has melted and you have a smooth and shiny sauce.
Dip the top of the profiteroles into the chocolate sauce and leave to cool.
«Once the profiteroles are cooked they will keep in an airtight container for a few days. Make sure they are cool before you place them in the container.»