Tick off the ingredients as you buy them
To make chocolate sauce, stir condensed milk in a small saucepan, over medium heat until hot. Add chocolate. Whisk until smooth before whisking in milk and rum. Remove from heat and cover to keep warm.
To begin making the churros dough, bring the milk, sugar, butter and vanilla beans and seeds to a boil in a medium saucepan. Discard the vanilla beans and then remove the saucepan from heat.
Sift the flour into the milk, sugar, butter and vanilla mixture. Stir with a wooden spoon until combined and dough comes away from side of pan. Remove from heat and stand, covered with plastic wrap, for 10 minutes.
Beat in egg yolks with wooden spoon or in the mixer, one at a time. Spoon the dough into a piping bag fitted with a 2cm, n9 or n11 star nozzle.
Heat oil to 180°C (when a cube of bread turns golden brown, oil is hot enough). Pipe 5cm lengths into oil, cutting off the dough with a sharp knife.
Deep fry churros until golden brown, then drain on absorbent paper. Dust with caster sugar and serve with warm chocolate sauce.