Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.
Unfold the thawed puff pastry sheet onto a lightly floured surface. If it's still cold, let it sit for a few minutes to become more pliable.
1 sheet Puff pastry
In a small bowl, mix together the granulated sugar and ground cinnamon.
1 sheet Puff pastry
Brush the puff pastry sheet evenly with the melted butter.
1 sheet Puff pastry
Sprinkle the cinnamon-sugar mixture evenly over the buttered pastry.
1 sheet Puff pastry
Starting from one of the longer sides, carefully roll up the puff pastry tightly into a log. Press lightly to seal the edge.
Cut the log into 12 even slices, about 1/2 inch thick.
Place the cinnamon twists onto the prepared baking sheet, leaving some space between them.
Bake for 10-12 minutes, or until golden brown and puffed up.
While the twists are baking, prepare the glaze by whisking together the powdered sugar and milk until smooth. Add more milk if a thinner glaze is desired.
1 sheet Puff pastry
Once baked, remove the cinnamon twists from the oven and let them cool slightly on the baking sheet. Drizzle with glaze if using.
Notes
These cinnamon twists are best served warm, but are also delicious at room temperature.