In a medium saucepan over medium heat, combine water, unsalted butter, 2 tablespoons sugar, and fine salt; bring to a gentle boil and stir until butter melts fully

Remove the saucepan from heat and add the all-purpose flour all at once, stirring vigorously until the mixture forms a smooth dough and pulls away from the sides of the pan

Allow the dough to cool for about 4–5 minutes so it’s warm instead of hot

Stir in the egg and vanilla extract until the mixture thickens and becomes glossy

Preheat the air fryer to 190°C (375°F); lightly spray the basket with cooking spray

Transfer the dough into a piping bag fitted with a large star tip (or use a zip-top bag with the corner snipped)

Pipe bite-sized portions of dough onto a piece of parchment paper or directly into the air fryer basket, keeping space between pieces

Air fry the churro bites for about 10–12 minutes until they are golden brown and puffy on the outside

While the churros cook, combine the coating sugar and ground cinnamon in a shallow bowl

If desired, brush the warm churro bites with melted butter, then immediately toss them in the cinnamon sugar until fully coated

Serve warm with your favorite sweet dipping sauce