Firstly, prepare the pastry cream. Pour the milk into a saucepan and add the vanilla extract, bring to the boil. Then, Beat the egg yolks in a bowl with the sugar then sift in the corn flour and flour. Pour the boiling milk over the egg mixture and whisk to combine. Pour the egg and milk mixture back into the saucepan and bring back to the boil, stirring continuously for 3 – 5 minutes until thickened. Remove from the heat and stir in the chocolate pieces. Mix well until the chocolate is fully combined. Set aside to cool down in a bowl with a layer of cling film layered over the mixture.

In the meantime, preheat the oven at 170°C. Sift the flour into a bowl. Pour the milk into saucepan and add the butter. Bring the mixture to the boil.

Remove from the heat and immediately add the flour, stirring vigorously. Return to a low heat and continue stirring until all the flour has been fully incorporated and the mixture form a smooth ball. Remove from the heat and transfer the mixture into a bowl. Add the eggs one at a time beating thoroughly after each addition, beat until smooth and glossy. Fill a piping bag, set with a 10 mm nozzle and pipe onto trays lined with parchment paper. Pipe 6cm eclairs. Brush with some egg wash then sprinkle the pearl sugar. Place in the oven and bake for 20-25 minutes until fully cooked. Turn off the oven and leave the door slightly ajar until the choux are cooled. This will help the choux to dry and keep them hollow.

When the choux have completely cooled down, pierce the base of the choux with a skewer and pipe in the cooled chocolate pastry cream. Sprinkle with icing sugar and serve within a day.