In a pot, combine water, sugar, and salt. Bring to a boil, then stir in flour and cinnamon until it forms a dough. Pipe into hot oil and fry until golden brown.

In a saucepan over medium heat, simmer the heavy cream. Remove from heat and stir in chopped dark chocolate until smooth. Add vanilla extract.

Transfer chocolate fondue to a bowl or fondue pot and arrange churros around it for dipping.