In a small saucepan over medium heat, combine the water, sugar, salt, and vegetable oil. Bring to a boil.
Remove from heat and immediately stir in the flour until the mixture forms a ball.
Heat vegetable oil in a deep-fryer or large saucepan to 375°F (190°C).
Spoon the dough into a pastry bag fitted with a large star tip.
Pipe strips of dough into the hot oil, cutting them with scissors to your desired length.
Fry the churros until golden brown and crispy, about 2-3 minutes per side.
Remove the churros from the oil and drain on paper towels.
In a shallow dish, mix together the sugar and ground cinnamon.
Roll the warm churros in the cinnamon sugar mixture until well coated.
In a small saucepan, heat the heavy cream over medium heat until it begins to simmer.
Remove from heat and add the chopped dark chocolate. Let it sit for a minute, then stir until smooth and well combined.
Enjoy your meal!