In a saucepan, combine sugar, cocoa and milk, stirring with a whisk until completely combined and smooth.

Turn heat on stove to medium and stirring occasionally, bring to a boil.

Stir in butter and continue to boil until sauce thickens, about 5 minutes.

Remove from heat, stir in vanilla and salt. Let cool for 5 minutes before serving.

Bring milk, sugar, and butter to a boil in a medium saucepan.

Sift in flour. Stir with a wooden spoon until combined and dough comes away from side of pan. Remove from heat.

Stand, covered with plastic wrap, for 3 minutes.

Beat in egg yolks with wooden spoon, one at a time.

Spoon dough into a piping bag fitted with a 2cm star nozzle.

Heat oil to 180°C (350°F)

Pipe 2 inches lengths into oil, cutting off the dough with a sharp knife or scissors. Deep fry churros until golden brown, then drain on absorbent paper.

Dust with caster sugar and cinnamon, and/or serve with chocolate sauce.