Combine the melted butter, vanilla paste and a pinch of salt with 500ml recently boiled water.
Sift the self-raising flour and plain flour into a large bowl. Mix together, then make a well in the centre. Gradually pour into the flour, stirring constantly to incorporate.
Cover with a warm, damp cloth and leave to rise for 20 minutes.
Put the dried chillies in a bowl filled with hot water and soak for 10 minutes. Remove with a slotted spoon and allow to cool. Squeeze out the excess water and finely chop.
Set a saucepan with the cream over a medium heat and bring to a simmer. Add the chocolate, coffee and chillies and stir constantly until the chocolate has completely melted. Pass the sauce through a sieve into a pan and discard the chillies. Keep warm over a low heat.
Fill a deep, heavy-based saucepan three-quarters full with oil and heat until a piece of dough turns golden brown in 30 seconds. Spoon the dough into a piping bag fitted with a small star-shaped nozzle. Hold the piping bag over the hot oil and carefully pipe 12cm-long shapes around the inside edge of the pan. Use scissors to snip off the lengths of dough.
Fry the churros for 30 seconds-1 minute, turning halfway, until golden. Remove with a slotted spoon and drain on kitchen paper. Keep warm while you fry the remaining dough.
Combine the sugar and cinnamon in a deep-sided baking tray. Toss the churros in the cinnamon sugar, coating well. Serve immediately with a bowl of the warm chocolate, coffee and chilli sauce on the side.