Step 1

Combine the water, butter, sugar, and salt in a medium saucepan and bring to a boil over medium heat, stirring occasionally until the butter melts. Reduce the heat to low and add the flour all at once, stirring vigorously with a wooden spoon until the dough forms a smooth ball, about 1 minute.

Step 2

Transfer the dough to the bowl of an electric mixer fitted with the paddle attachment (or use a hand mixer with beaters). Let it cool for about five minutes. On medium-low speed, beat in the vanilla, then add the eggs one at a time, mixing well and scraping down the sides of the bowl after each addition. Once all the eggs are incorporated, continue mixing for 1 minute more, until the dough is smooth, thick, and pipeable.

Step 3

Pour about two inches of vegetable oil into a heavy-bottomed pot or deep skillet and heat it to 350°F (175°C) over medium heat. (If a cube of bread sizzles when you drop it in, it's ready.)

Step 4

In a shallow dish that’s large enough to fit a 6-inch (15-cm) churro, stir the cinnamon and sugar together. Set aside.

Step 5

Line a baking sheet or plate with a few layers of paper towels and put by the stove.

Step 6

Transfer the dough to a piping bag fitted with a large star tip. Pipe 6-inch (15-cm) strips of dough directly into the hot oil, using scissors to cut the dough. Fry in batches, being careful not to overcrowd the pot and adjusting the heat as necessary to maintain the temperature, 4 to 5 minutes, turning once as the underside browns. Remove with tongs or a slotted spoon and drain on a paper-towel-lined baking sheet or plate.

Step 7

While still warm, roll the churros in the cinnamon-sugar mixture to coat. Serve the churros immediately with chocolate sauce, or enjoy them on their own.

Step 8

Heat the heavy cream in a small saucepan over medium heat until it just begins to boil. Remove from the heat and add the chocolate chips, cinnamon, and salt; whisk until smooth and glossy.