Mix the dark caster sugar and cinnamon in a bowl.
When the dough has doubled in size, put it on a surface that is lightly covered with flour. Don't use too little flour, because the dough will stick and you will not be able to make a beautiful cinnamon roll.
Roll out the dough with a rolling pin to a rectangular piece of 40x50 centimeters.
Brush the dough with the butter (that is on room temperature). Leave about 2 centimeters space on every side uncovered.
Sprinkle the caster sugar/cinnamon mixture on top of the butter.
Pick up the bottom of the dough on the long side and roll it up until you have a roll.
Cut the roll with a sharp knife in 12 pieces. Each piece should be about 4 centimeters thick.
Cover a baking pan with baking paper and put the cinnamon rolls. Don't put them tightly against each other, because they need room to rise.
Cover the cinnamon rolls with plastic foil or a damp cloth and let it rise for another 30 minutes, until doubled in size.
Heat the oven until 200 degrees celcius (390 F).
Once the cinnamon rolls have doubled in size bake them in the oven for about 15 minutes or until they are golden brown.