Preheat the oven to 220°C / 425°F / Gas mark 7. Line two baking trays with parchment paper.
To make the pastry, combine the water and the butter together in a saucepan over a medium heat. Bring it to the boil before removing from the heat and adding the flour.
Mix the flour with the butter mix until it is a smooth consistency. It will look like a ball of dough.
Leave to cool before putting it into a mixing bowl. Beat in the egg and keep beating until the mixture is smooth.
Spoon into a pastry bag and pipe 12 sausage-like shapes onto the baking tray.
Place in the oven for 20 minutes until golden and crispy.
Remove from oven and allow to cool slightly so that you can cut a slit into each side.
While they are cooling you can make the filling. Mix the cream with the icing sugar until it is like whipped cream. Place into a pastry pipe and pipe out onto each eclair..
To make the topping, melt the chocolate in a small bowl over a pot of boiling water. Spoon the chocolate over each eclair and leave to set.
Put a few berries in the centre before serving.