In a medium saucepan, combine the water, butter, 2 tablespoons of sugar, and salt. Bring the mixture to a gentle boil over medium-high heat. Ensure the butter is completely melted before moving to the next step.
Turn the heat down to low and add the flour all at once. Stir vigorously with a wooden spoon or spatula 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 eggs one at a time, beating well after each addition. The dough may look like it is separating at first, but keep stirring until it becomes smooth and glossy. Stir in the vanilla extract.
Transfer the dough into a pastry bag fitted with a large star tip. Line your air fryer basket with a piece of perforated parchment paper or lightly grease it. Pipe 4-inch strips of dough into the basket, leaving space between each one so they do not touch.
Lightly spray the tops of the churros with cooking spray. Cook in the air fryer at 375°F (190°C) for 10 to 12 minutes, or until they are golden brown and crispy. You may need to work in batches depending on the size of your air fryer.
While the churros are cooking, mix the remaining 1/2 cup of sugar and cinnamon in a shallow bowl. As soon as the churros come out of the air fryer, lightly brush them with a tiny bit of melted butter or spray them again, then toss them in the cinnamon-sugar mixture until well coated.
Place the chocolate chips and heavy cream in a small microwave-safe bowl. Heat in 30-second intervals, stirring in between, until the sauce is smooth and melted. Serve the warm churros immediately with the chocolate sauce for dipping.