Flatten the butter Block straight out of the fridge between two sheets of parchment paper to around 20 x 15 cm.
Roll out dough at 3 °C to double of the dice of your butter sheet (20 x 30 cm) and make sure the butter is flexible, but not to soft.
Do a french lock in and roll out the dough to a length of around 80 cm.
Do a book fold (4 layers)
Rest 30 min in the fridge.
Roll out to 60 cm and do a single fold (3 layers).
Rest 60 min in the fridge.
Roll out the dough to 40 cm in width and around 40 - 50 cm in length, or a far as you come with the dough. Depending on your flour this could be more or less.
If the dough is springing back to much you can rest again in the fridge for 30 min.
Roll out to 100% (40 cm width / 50 cm length).
Cut into croissant 8 x 40 cm.
Prove for 3 h in the oven at 28 °C with just the oven light on. Put a small glass (200 ml) of boiling water in the bottom of the oven to help achieve a good humidity. Change the boiling water after 1 hour.
Bake at 200 °C fan assisted for 20 min
Mix sugar and water together for the syrup and heat for 20-30 seconds in the microwave.
Brush thinly with syrup.
Bake for another 2 min.