In a shallow dish, whisk together the granulated sugar and ground cinnamon to create the cinnamon sugar mix. Set it aside.

In a medium saucepan, combine the water, butter, and salt. Place it over medium heat and bring to a rolling boil.

Turn the heat down to low and add the all-purpose flour all at once. Stir vigorously until the mixture forms a thick, cohesive ball of dough, about 60 seconds.

Transfer the hot dough ball to the bowl of a stand mixer fitted with a paddle attachment and let it cool for 5 to 10 minutes.

With the mixer on low speed, add the eggs one at a time, ensuring the first egg is completely incorporated before adding the second. Beat in the vanilla extract.

Spoon the dough into a piping bag fitted with a large star tip.

Preheat your air fryer to 375°F (190°C). Lightly spray the air fryer basket with cooking spray.

Pipe 4 to 5 inch lengths of dough into the basket, using kitchen scissors to snip the dough. Work in batches, leaving space between churros.

Air fry for 8 to 12 minutes or until the churros are a deep golden brown and feel crisp to the touch.

As soon as the churros come out of the air fryer, use a pastry brush to lightly coat them with melted butter, then roll them in the cinnamon sugar mixture until generously coated. Serve warm.