In a medium saucepan, combine the water, butter, sugar, and salt. Bring it to a boil over medium-high heat. Stir occasionally to ensure the butter melts evenly.

Once the mixture starts to boil, reduce the heat to medium-low and add the flour. Stir constantly with a wooden spoon or rubber spatula until the dough comes together and becomes smooth. This should take around 3-4 minutes. Remove the saucepan from heat and let the dough cool for 4 minutes.

Add the eggs and vanilla extract. Mix the dough with an electric mixer (or by hand) until smooth. The dough should resemble thick mashed potatoes.

Transfer the dough into a large piping bag fitted with a star-shaped nozzle. Pipe the churros into 4-inch lengths onto a parchment-lined baking sheet. Cut the dough with scissors.

Refrigerate the piped churros for 30 minutes to an hour to help them maintain their shape while cooking.

Preheat the air fryer to 375°F (190°C) and lightly spray the basket with oil.

Carefully transfer the piped churros to the air fryer basket, leaving space between each. Air fry for 10-12 minutes or until golden brown, flipping halfway through.

While the churros are cooking, mix the sugar and cinnamon in a shallow bowl.

Once the churros are done, immediately transfer them to the cinnamon-sugar mixture and toss to coat.

Serve warm with your favorite dipping sauce, such as chocolate, caramel, or whipped cream.