Preheat your air fryer to 375°F (190°C) for at least 10 minutes. This ensures the basket is hot enough for the churros to immediately start crisping. Generously spray the basket with cooking spray—this step is crucial for preventing sticking.

In a medium saucepan, combine the butter, milk, water, sugar, and salt. Warm over medium-low heat, stirring until the butter melts and everything blends into a smooth mixture. Increase heat to medium-high and bring to a gentle simmer.

Remove the pan from heat. Add the flour all at once and vigorously stir with a wooden spoon until it forms a thick paste. Return to medium heat and cook for 1–2 minutes, stirring continuously, until the dough pulls away from the pan and looks glossy and smooth.

Immediately scrape the dough into the bowl of a stand mixer fitted with the paddle attachment. Beat on low for 30 seconds to release steam. Add the eggs one at a time, mixing until each is fully incorporated before adding the next. Once all eggs are in, beat on medium-high for 15 seconds to finish the dough.

Transfer the dough to a piping bag with an open star tip. Pipe 4½–5 inch-long churros directly onto the greased air fryer basket, leaving space between each for air circulation. Use kitchen shears to cleanly snip each strip of dough.

Air fry the churros for 10–12 minutes, or until deeply golden, crisp, and puffed. Cool in the basket for 5 minutes, then transfer to a wire rack.

In one bowl, whisk the sugar and cinnamon. In another, pour the melted butter. Dip each churro briefly in butter, then roll in cinnamon sugar until fully coated.

Enjoy warm, ideally immediately after coating. They also pair beautifully with chocolate sauce, dulce de leche, or vanilla glaze.