For the Churros:

1. Prepare the Dough:
   In a medium saucepan, combine water, sugar, salt, and butter. Bring the mixture to a boil over medium heat.

2. Add the Flour:
   Remove the saucepan from the heat and stir in the all-purpose flour all at once. Mix until a smooth dough forms. The dough should be thick and come away from the sides of the pan.

3. Cool and Beat:
   Transfer the dough into a mixing bowl and let it cool for a few minutes. Once it’s cool enough to handle, add the eggs, one at a time, beating well after each addition. Stir in the vanilla extract.

4. Prepare to Fry:
   Spoon the dough into a piping bag fitted with a large star tip. This star-shaped tip will give the churros their signature ridged texture.

5. Heat the Oil:
   Heat vegetable or canola oil in a deep fryer or large pot to 350°F (175°C). Use a thermometer to ensure the oil is at the right temperature for frying.

6. Fry the Churros:
   Pipe 4–6 inch strips of dough directly into the hot oil. Use scissors to cut the dough after each strip. Fry the churros for 2–3 minutes on each side, until they are golden brown and crispy.

7. Drain and Coat in Cinnamon Sugar:
   Once fried, remove the churros from the oil and place them on paper towels to drain excess oil. While still warm, roll them in a mixture of ½ cup sugar and 1 tsp ground cinnamon to coat them evenly.

For the Chocolate–Dulce de Leche Dipping Sauce:

1. Heat the Cream:
   In a small saucepan, heat the heavy cream over medium heat until it is just simmering. Keep a close eye on it to avoid boiling.

2. Melt the Chocolate:
   Remove the saucepan from the heat and add the chopped chocolate to the cream. Let it sit for 1 minute to allow the chocolate to soften.

3. Combine with Dulce de Leche:
   Stir the mixture until the chocolate is completely melted and smooth. Add the dulce de leche and a pinch of sea salt, stirring until everything is well combined and glossy.

4. Serve Warm:
   Pour the dipping sauce into a small bowl and serve warm alongside the churros.