To make the choux pastry, put 200 ml water, 4 tsp caster sugar and 85 g butter in a saucepan and heat gently to melt the butter.
Turn up the heat and tip in 115 g plain flour and a pinch of salt and beat vigorously, removing from the heat, until the mixture
forms a smooth paste and comes away from the sides of the pan. Transfer the mixture to a large bowl and leave to cool. Beat in
3 eggs, one at a time, until the mixture is smooth and glossy. Lightly butter a large baking sheet, put a plain 1 cm nozzle into
a piping bag then fill it with the mixture and pipe small balls in lines on the baking sheet. With a wet finger, press down the
pointy tips of the balls. Heat the oven to 200°C and place a cup of water into a roasting pan at the bottom of the oven – this
creates steam to help the pastry rise. Put the choux pastry balls into the oven and bake for 25 – 30 minutes, until golden brown
and crispy. Remove from the oven and puncture the base of each profiterole with a skewer, put back onto the baking tray with the
bases facing upwards and return to the oven for another 5 minutes, to dry out the profiteroles. Remove and let cool. Whip 600ml
double cream with the zest of an orange until stiff, fill a piping bag with a 1/2 cm nozzle and stuff the profiteroles with the
whipped cream. Pile the profiteroles onto a plate to form a cone. Put 100 ml water and 80 g caster sugar into a saucepan and bring
to a simmer. Break 200 g dark chocolate into small pieces and put into a bowl over simmering water, and when melted, pour in the
syrup mixture and stir until smooth and shiny. When cool, pour the chocolate sauce over the profiteroles and serve.