In a medium bowl, whisk together the granulated sugar, ground cinnamon, and salt until evenly combined.

Lightly flour a clean work surface. Unfold the puff pastry sheet onto the surface and gently roll or stretch it into an even rectangle.

Brush the entire surface of the puff pastry with the melted butter, reaching all the way to the edges.

Sprinkle the cinnamon sugar mixture evenly over the buttered pastry, then gently press it into the surface with your hands so it adheres.

Using a sharp knife or pizza cutter, cut the pastry lengthwise into 12 strips, each about 1 inch wide.

Working one strip at a time, pick up each strip by the ends, twist it several times into a spiral, and lightly pinch the ends so they hold their shape.

Preheat the air fryer to 350°F.

Arrange the twisted strips in a single layer in the air fryer basket, leaving a little space between each for air circulation.

Air fry at 350°F for 8 minutes, flipping the twists halfway through, until puffed, golden brown, and crisp.

Transfer the cinnamon twists to a wire rack and let them cool slightly so the layers set.

For the optional glaze, whisk together the powdered sugar and milk or water in a small bowl until smooth.

Drizzle the glaze over the slightly cooled cinnamon twists and serve warm or at room temperature.