Line a small baking sheet with parchment. Fit a large star tip (like 1m) in a piping bag or gallon-size resealable plastic bag. To a medium pot on medium-high, add the butter, 1 tablespoon sugar and the water. Add a pinch of salt and bring mixture to a boil. Once boiling, reduce heat to medium-low. Add the flour and stir rapidly with a wooden spoon until a dough forms. Cook 4-5 minutes, stirring constantly, until mixture has thickened and does not stick to sides of pot.

Transfer dough to the bowl of a stand mixer. With a paddle attachment, mix dough on medium-low 3-5 minutes, until slightly cooled. Once cooled, add the eggs, one at a time, mixing constantly until fully incorporated. Add the vanilla and mix until combined. Transfer dough to prepared piping bag. Pipe dough into 3-4-inch lines, using kitchen scissors to cut off dough pieces. Freeze 30 minutes.

Preheat air fryer to 375 degrees F. In batches, add churros to air fryer basket, leaving space between churros. Spray tops lightly with the cooking spray. Cook 10-12 minutes, until golden brown. Meanwhile, in a shallow bowl, combine remaining 1/4 cup sugar with the cinnamon. Transfer hot churros to sugar mixture and toss to coat. Repeat with remaining churros. Add the chocolate-hazelnut spread to a microwave-safe bowl. Microwave spread 30 seconds, until warm. Add warmed spread to a serving platter with churros and serve.