Add the water, butter, salt, and cinnamon to a pan or pot. While on medium heat, melt everything together and bring the mixture to a boil. Turn the heat on low.
Add all the flour at once and stir quickly and vigorously to evenly mix the ingredients as a dough ball will form quickly. Immediately remove from the heat when that happens. Let it rest for 5 minutes.
Transfer the dough to a bowl and stir in the eggs, one at a time, until combined. Pour the churro dough into a piping bag that has a large star tip.
Preheat the air fryer to 375 degrees F for 3-5 minutes. Then add your churro into the air fryer basket; depending on the size of your air fryer, you may need to cook these in batches. Leave plenty of space between the churro bites. Cook for 10-12 minutes; for added flavor, brush the churro bites with melted butter during cooking.
In a bowl, mix the sugar and cinnamon for the churro’s topping. Place each churro bite in the bowl and toss around to coat thoroughly.
Serve while still warm, and enjoy with your favorite dipping sauce!