Preheat the oven to 180°c (160 fan/ Gas 4/ 350F) and line 2 baking trays with non stick baking paper.
Mix together the softened butter, cinnamon, and sugars in a bowl until you get a paste (it will take a few minutes).
60 g Butter, 30 g Light Brown Sugar, 30 g Demerara Sugar, 2 tablespoon Cinnamon
Unroll the puff pastry sheet (keeping it on the paper it came wrapped up in) and spread the cinnamon sugar evenly over the top of the pastry, leaving a 1cm gap on the bottom long edge of the pastry sheet. Brush the bottom edge with egg wash.
375 g Puff Pastry Sheet, 1 Egg
Using the paper sheet that came with the ready-rolled puff pastry sheet to help you, tightly roll up the pastry on the long edge and press to seal.
Using a sharp knife (or string), cut 2cm slices and place them cut side up on a baking sheet lined with non-stick parchment paper. Glaze the tops with the egg wash.
Bake in the oven for 20-25 minutes until golden brown.
Leave the swirls to cool on the baking sheet for 5 minutes, before removing them to a wire rack. Mix the icing sugar with a little water to make a runny icing and use a spoon to drizzle it over the swirls.
2 tablespoon Icing Sugar