In a medium saucepan, combine water, softened unsalted butter, salt, and sugar. Bring to a boil over medium heat, stirring occasionally. Reduce heat and gradually add plain flour, stirring until a smooth dough forms, about 2-3 minutes.

Let the dough cool for 4-5 minutes, then add the egg and vanilla essence, and beat until smooth.

Preheat your air fryer to 375°F (190°C) for about 5 minutes.

Prepare a piping bag with a star tip, fill it with churro dough, and lightly spray the air fryer basket with nonstick spray. Pipe small churro shapes, leaving space between each.

Brush churros lightly with melted butter, then cook for 10-12 minutes until golden brown.

Remove churros from the air fryer and toss in a mixture of white sugar and cinnamon while warm.