In a medium saucepan, combine the water, butter, two tablespoons of sugar, and salt. Bring the mixture to a boil over medium heat, ensuring the butter is completely melted.
Reduce the heat to low and add the flour all at once. Stir vigorously with a wooden spoon until the mixture forms a smooth ball of dough that pulls away from the sides of the pan. Continue to cook and stir for about 1 minute to “cook out” the raw flour taste.
Remove the pan from the heat and let the dough cool for about 5 minutes. Add the egg and vanilla extract. Beat the mixture vigorously until the egg is fully incorporated and the dough becomes smooth and glossy again.
Transfer the dough into a piping bag fitted with a large star tip. Line your air fryer basket with a piece of parchment paper (perforated if possible). Pipe 3-inch lengths of dough into the basket, snip the ends with scissors, and leave space between each one to allow for air circulation.
Lightly spray the churros with a bit of cooking oil spray. Air fry at 375°F (190°C) for 8 to 10 minutes, or until they are deeply golden brown and firm to the touch. You may need to work in batches depending on the size of your air fryer.
While the churros are cooking, mix the 1/2 cup of sugar and cinnamon in a shallow bowl. Immediately after removing the churros from the air fryer, toss them in the cinnamon-sugar mixture until evenly coated.
Place the chocolate chips and heavy cream in a small microwave-safe bowl. Microwave in 20-second intervals, stirring in between, until the sauce is completely smooth and melted. Serve warm alongside the churros.