In a medium saucepan, combine the water, butter, salt, and sugar. Bring to a boil over medium-high heat, stirring occasionally to dissolve the sugar.

Once boiling, reduce the heat to low and add the flour all at once. Stir vigorously with a wooden spoon until the dough pulls away from the sides of the pan and forms a smooth ball. This should take about 1 to 2 minutes.

Turn off the heat and remove the pan from the stove. Allow the dough to cool for about 4 to 5 minutes.

Transfer the slightly cooled dough to a large mixing bowl. Add the vanilla extract and the egg.

Use a sturdy wooden spoon or an electric hand mixer on low speed to beat the egg into the dough. It may look separated at first, but keep mixing until smooth and pipeable.

Spoon the dough into a piping bag fitted with a star-shaped tip (this gives that classic churro ridged look). If you don’t have a piping bag, a heavy zip-top bag with the corner snipped off will work in a pinch.

Preheat the air fryer to 375°F (190°C). Lightly spray the basket with a neutral oil spray like avocado or coconut oil.

Pipe bite-sized portions of dough directly into the air fryer basket, leaving some room between them for airflow. Alternatively, you can drop spoonfuls of dough if you prefer a more rustic shape.

Lightly brush or spray the tops of the churros with a little melted butter or neutral oil to encourage browning.

Air fry for 10 to 12 minutes, turning once if needed, until they are golden brown and puffed.

Depending on the size of your air fryer, you may need to work in batches.

In a shallow bowl, mix the granulated sugar and cinnamon powder.

While the churro bites are still warm, transfer them directly from the air fryer to the cinnamon-sugar mixture and toss until they are evenly coated. If needed, lightly brush them with melted butter to help the sugar mixture stick.

Serve warm, with your favorite dipping sauces like chocolate ganache, Nutella, caramel, or even honey. These churro bites are best enjoyed fresh but can be stored and reheated if you have leftovers.