Melt butter in a saucepan over medium-high heat. Stir in milk and salt. Reduce the heat to medium and bring to a boil, continuously stirring with a wooden spoon. Quickly add flour all at once and keep stirring until the dough comes together.

Remove from the heat and let cool for 5 to 7 minutes. Mix in eggs with the wooden spoon until incorporated. Spoon dough into a pastry bag fitted with a large star tip. Pipe dough directly into the air fryer basket, making six equal strips.

Air fry churros at 340 degrees F (175 degrees C) for 5 minutes.

Meanwhile, mix sugar and cinnamon together in a small bowl until well combined. Pour onto a shallow plate.

Remove churros from the air fryer and roll in the cinnamon sugar to coat.