Preheat the oven to 220°C/425°F (without fan).
Line a baking sheet with baking paper.
In a small saucepan, heat the water with the salt, sugar and butter until the butter has melted and the water begins to boil.
Remove the pan from the heat and quickly stir in the flour until the mixture comes together into a smooth ball.
Tip the mixture into the bowl of an electric stand mixer and beat it a little to release some of the heat.
Allow the mixture to cool for about 2 minutes. Using the flat paddle attachment, beat in the eggs, one at a time, until the dough is thick, smooth and shiny.
Alternatively, you can do steps 5 and 6 by hand but it will require a bit of upperbody workout.
Leave the mixture to cool completely, otherwise the chocolate chips will melt.
Stir in the chocolate chips.
Fill a piping bag, fitted with a 1 cm round nozzle, with the dough and pipe small balls of dough onto the baking sheet.
Generously sprinkle with pearl sugar and bake for 13 to 15 minutes, or until they are puffed and golden.