In a medium shallow bowl, whisk together 1/2 cup sugar and 1/2 teaspoon cinnamon. Set aside.
Prepare Dough:
In a medium saucepan over medium heat, combine water, milk, vanilla, butter, salt, 2 tablespoons sugar, and 1/4 teaspoon cinnamon.
Bring the mixture to a rolling boil, stirring frequently.
Reduce heat to low.
Add flour and stir constantly with a wooden spoon until the mixture forms a thick, smooth ball and appears to dry out (a thin film will form on the bottom of the pan), about 2-3 minutes.
Beat the Dough:
Immediately transfer the dough to a large bowl.
Beat on medium speed with a hand mixer (or stand mixer) for 2 minutes to cool the mixture slightly.
Add Eggs:
Add in eggs, one at a time, beating well after each addition, until fully combined. The mixture should appear smooth and creamy.
Chill Dough:
Spoon the dough into a piping bag fitted with a large open star tip (e.g., Ateco 829).
Place in the fridge and chill for 30 minutes.
Preheat Air Fryer:
Preheat the air fryer to 380°F. Spray the basket with nonstick spray.
Pipe Churro Bites:
Working in batches, hold the piping tip close to the basket and pipe strips of dough (2 & 1/2 inches long) in a single layer. Cut the end with kitchen scissors.
Repeat until the churro bites fill the basket without over-crowding.
Air Fry:
Air fry until golden, 8 to 10 minutes.
Coat with Cinnamon Sugar:
Immediately out of the air fryer, brush the churro bites with melted butter.
Roll them in the cinnamon-sugar mixture.
Repeat:
Repeat the process with the remaining dough.
Serve:
Enjoy the churro bites immediately as is or with some chocolate dipping sauce!
Notes
Don't brown the butter mixture: Bring the mixture to a boil but do not let it brown before you reduce the heat.Cool the batter before adding eggs: Mix the batter to cool it down before adding the eggs. If you add the eggs immediately, they may scramble instead of incorporating into the dough.Don't crowd the air fryer: Only add as many churro bites as will fit in the air fryer in a single layer. Overcrowding the basket can lead to uneven cooking and a lack of golden brown color.Add sugar immediately: As soon as the churros come out of the air fryer, coat them with melted butter and toss in the cinnamon-sugar. If you wait until they cool, the sugar won't stick.