Preheat your oven to 375°F (190°C) and grease a 12-cup muffin tin.
Roll out the puff pastry and brush it with melted butter.
Mix cinnamon and sugar together, then sprinkle evenly over the buttered pastry.
Cut the pastry into 1-inch wide strips, roll them up like a cinnamon roll, and place into muffin cups.
Bake for 18-20 minutes until golden brown and puffed up.
Let them cool slightly, then brush with more butter and roll in additional cinnamon sugar.
Optional: Use a piping bag to fill the center with pastry cream or Nutella.