In a medium saucepan, combine the water, granulated sugar, salt, and vegetable oil. Bring to a boil over medium heat.
Remove from heat and immediately stir in the all-purpose flour. Stir vigorously until the mixture forms a ball.
Let the dough cool slightly, then beat in the eggs one at a time, mixing well after each addition. Stir in the vanilla extract until the dough is smooth and glossy.
Heat about 2 inches of vegetable oil in a large, heavy-bottomed pot over medium-high heat until it reaches 375°F (190°C).
While the oil is heating, transfer the dough to a piping bag fitted with a large star tip.
Carefully pipe 4-6 inch lengths of dough into the hot oil, using scissors to cut the dough as you pipe. Fry the churros in batches, turning occasionally, until golden brown and crispy, about 2-3 minutes per side.
Remove the churros from the oil with a slotted spoon and drain on paper towels.
In a shallow dish, mix the granulated sugar and ground cinnamon.
While the churros are still warm, roll them in the cinnamon sugar mixture to coat evenly.
In a small saucepan, combine the dulce de leche and heavy cream. Heat over low heat, stirring constantly, until the sauce is warm and smooth.
Enjoy your meal!