Combine superfine sugar and cinnamon in a wide shallow dish; set aside for coating.

In a bowl, stir together flour, baking powder and salt. Beat in olive oil and freshly boiled water until you have a warm, sticky dough. Let rest about 10 minutes while oil heats.

Heat vegetable oil in a saucepan to about 170 °C (350 °F). A cube of bread should brown in ~30 sec.

Meanwhile, prepare the chocolate sauce: in a small heavy saucepan over low heat, melt dark and milk chocolate with golden syrup and cream, stirring until smooth. Keep warm off heat.

Fit a piping bag with a large star-shaped tip (~8 mm). Transfer dough into bag. Pipe short 1½–2″ lengths directly into hot oil, cutting with scissors. Fry 3–4 at a time until crisp and golden (~3 min).

Lift churros with a slotted spoon onto paper towels, then immediately toss in cinnamon sugar mixture. Keep warm in a low oven if needed.

Serve churros warm with individual cups of the chocolate dipping sauce. Dunk and enjoy!