Mix ¼ cup of superfine sugar and 2 teaspoons of ground cinnamon in a shallow dish.
Mix 1 cup of all-purpose flour, 1 teaspoon of baking powder, and 1 pinch of salt. Stir in 1 tablespoon of vegetable oil and 1 cup of boiling water just until a thick, sticky dough forms.
Transfer to a sturdy piping bag fitted with a ⅓in / 8mm star tip.
Pour 2 cups of neutral frying oil into a deep pan, adding more if needed to reach 2in / 5cm deep. Heat the oil to 340°F / 170°C.
Pipe 6in / 15cm lengths close to the oil surface, cutting with scissors. Fry in small batches for 2-3 minutes, turning until golden and crisp. Drain on paper towels, then roll in cinnamon sugar.
Microwave ½ cup of dark chocolate chips with ½ cup of heavy cream in 30-second bursts, stirring until smooth. Let stand for 5 minutes and serve with the hot churros.
