Make the Dough: In a medium saucepan, combine the water, butter, salt, and sugar. Bring to a boil over medium heat, stirring until the butter is melted.

Add Flour: Remove the saucepan from the heat and immediately add the flour all at once. Stir vigorously with a wooden spoon until a smooth dough forms and pulls away from the sides of the pan.

Incorporate Eggs: Transfer the dough to a stand mixer fitted with the paddle attachment (or use a hand mixer). Beat on medium speed for about 1 minute to cool the dough slightly. With the mixer running, add the eggs one at a time, beating well after each addition. The dough should be smooth and glossy. Stir in the vanilla extract.

Prepare for Air Frying: Transfer the dough to a piping bag fitted with a large star tip (or a round tip if you prefer).

Pipe and Cut: Lightly spray the air fryer basket with vegetable oil spray. Pipe the dough into 1-2 inch lengths directly into the air fryer basket, leaving some space between each bite. Use kitchen shears to cut the dough at the tip as you pipe.

Air Fry: Air fry at 375°F (190°C) for 8-10 minutes, or until the churro bites are golden brown and crispy. Check them halfway through and shake the basket gently for even browning.

Coat with Cinnamon Sugar: While the churro bites are air frying, combine the sugar and cinnamon in a shallow dish.

Coat and Serve: Immediately after removing the churro bites from the air fryer, toss them in the cinnamon-sugar mixture until evenly coated. Serve warm and enjoy!