• Preheat the oven to 220ºC (fan 200ºC)/425ºF/Gas mark 7
• Grease a large baking sheet and sprinkle with water

For the choux pastry

• Put the butter in a heavy-based saucepan with the water and heat until the butter melts. Bring to the boil
• Remove from the heat and add the flour and a pinch of salt. Stir vigorously
• When a smooth paste develops, return the pan to the heat, stirring. The mixture will dry out a little and form a soft ball that comes away from the sides of the pan
• Remove the pan from the heat again, leave the mixture to cool slightly, then gradually add the eggs, beating really well between each addition until the mixture is smooth and glossy
• Dollop tablespoons of the mixture onto the baking sheet leaving room between each for them to spread a bit
• Bake for 10 minutes, then reduce the heat to 190ºC (fan 170ºC)/375ºF/Gas mark 5 and bake for a further 20 minutes
• Transfer the profiteroles to a wire rack to cool completely. Once they've cooled, pierce the base of each to the diameter of your narrowest piping nozzle. If you don't have a piping bag & nozzle, slice each profiterole in half horizontally

For the filling

• Whip the whipping cream until firm, put into a piping bag fitted with a round, narrow nozzle and pipe it into the hole in the bottom of each profiterole. If you don't have a piping bag & nozzle, spoon a dollop on to the bottom half of each profiterole before replacing the top

For the the topping

• Put the chocolate and double cream into a heatproof bowl and set it over a pan of gently simmering water, stirring until smooth and shiny
• Remove the bowl from the pan and leave the sauce at room temperature for about 30 minutes, or until it is cool and thick enough to coat the profiteroles without dripping down the sides
• Carefully dip the top of each profiterole into the chocolate sauce