In a saucepan over medium heat, combine water, butter, sugar, and salt. Bring to a boil, then reduce heat and stir in the flour until a dough forms. Cook for 1-2 minutes, stirring constantly, until the dough pulls away from the pan.

Remove from heat and let cool for 5 minutes. Beat in eggs one at a time, ensuring each is fully incorporated before adding the next. Stir in vanilla extract until the dough is smooth and glossy.

Transfer the dough to a piping bag fitted with a star tip. Pipe 4-5 inch strips of dough onto a parchment-lined baking sheet.

Preheat the air fryer to 375°F (190°C). Lightly spray the air fryer basket with cooking spray or brush with oil. Arrange the piped churros in a single layer, leaving space between them.

Air fry for 10-12 minutes, flipping halfway through, until golden brown and crispy.

While still warm, brush the churros lightly with melted butter. Roll them in a mixture of granulated sugar and ground cinnamon until evenly coated.

Serve immediately with your favorite dipping sauces such as chocolate sauce, caramel, or dulce de leche.