200g plain flour
1 tsp caster sugar
good pinch salt
4 medium free-range eggs
FOR THE TOPPING AND FILLING
50g dark chocolate, chopped
150g icing sugar
2 tbsp cocoa powder
450ml double cream
Heat oven to 200C/180C fan/gas 6. Line a baking sheet with baking parchment. Mix the flour, sugar and salt together. Heat 250ml water and the butter in a saucepan over a low heat until the butter has melted. Increase the heat and as soon as it starts to bubble, tip in the flour mixture. Beat vigorously until mixture leaves the side of the pan and is smooth. Continue to cook for 2-3 mins. Remove the pan from the heat and leave to cool for a few mins.
Whisk eggs together, then gradually beat into the flour mixture, a little at a time, until smooth, glossy and thick enough to pipe (you may not need quite all the egg). Spoon the mixture into a piping bag fitted with a medium plain nozzle.
Pipe 10-12cm lines onto the baking sheet, spaced a little apart, and bake for 20-25 mins or until golden brown and crisp. Remove from the oven and set aside to cool on a wire rack.
Meanwhile, heat the dark chocolate and 2 tbsp water in a saucepan until the chocolate has melted. Sift the icing sugar and cocoa into a bowl, then add the melted chocolate and beat until the mixture is smooth and thickened. Whip the double cream just until stiff peaks form when the whisk is removed. Spoon the cream into a piping bag fitted with a plain nozzle. Carefully insert the nozzle into one end of each eclair and fill with cream.
Spread or pipe the chocolate fondant on top of the eclairs and leave until completely set before serving.