In a medium saucepan, combine the water, butter, caster sugar, and salt. Heat over medium heat until the butter is melted, and the mixture begins to boil.

Reduce the heat and stir in the plain flour and baking powder, mixing until the dough comes together. Cook for another 2-3 minutes, stirring constantly.

Remove the pan from the heat and let the dough cool for 5 minutes. Once cooled, beat in the eggs one at a time, ensuring each is fully incorporated before adding the next. Stir in the vanilla extract.

Transfer the dough into a piping bag fitted with a large star nozzle.

Heat the vegetable oil in a deep pan or fryer to 180°C. Pipe 10-12cm lengths of dough into the hot oil, using scissors to cut them off. Fry in batches for 2-3 minutes, or until golden and crispy.

Remove the churros from the oil and place them on paper towels to drain excess oil. While still warm, roll the churros in the cinnamon sugar mixture to coat.

For the chocolate dip, melt the dark chocolate in a heatproof bowl over a pan of simmering water or in the microwave, stirring until smooth.

Serve the churros with the melted chocolate dip for dipping.