In a saucepan, combine the water, butter, salt, and sugar. Bring the mixture to a boil over high heat. Once it begins boiling, reduce the heat to low and gradually stir in the flour. Continue mixing until the dough forms and pulls away from the sides of the pan. Turn off the heat.

Transfer the dough to a large mixing bowl and let it cool for about 4–5 minutes.

Add the egg and vanilla extract to the slightly cooled dough, then mix everything thoroughly using an electric hand mixer until well combined.

Spoon the mixture into a piping bag. Preheat your air fryer to 375°F. Lightly spray the air fryer basket with a neutral nonstick spray—coconut oil spray tends to work especially well here.

Pipe bite-sized portions of the dough directly into the basket, making sure not to overcrowd it. You may need to work in multiple batches. Alternatively, you can drop spoonfuls of dough into the basket if piping isn’t an option.

Lightly brush the tops of the churros with melted butter, then air fry for 12–15 minutes, or until golden brown and crisp (see notes below for cooking tips). Repeat with the remaining dough.

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

Once the churro bites are done, immediately toss them in the cinnamon sugar mixture until well coated.

If the coating doesn’t stick as well as you’d like, you can brush the churros with a bit of melted butter first—or mist them with water or cooking spray—before rolling them in the cinnamon sugar.

Serve warm with your favorite dipping sauce like chocolate syrup, honey, or Nutella.