Melt butter in microwave, then allow to cool for at least 20 minutes
In a small bowl, combine dark brown sugar and cinnamon
Using a pastry brush, spread the butter onto the dough. Spread to all edges, leaving a small border (a couple of centimetres) along one of the longer sides
Sprinkle the combined sugar and cinnamon over the butter, then press it into the butter
From the long side that's covered with cinnamon filling, start rolling tightly to form a long log, finishing at the side with no filling on the border
Using a large serrated knife, cut log into thirds, then each third into 3 again (giving you 9 rolls). Cut only towards you, rather than a sawing motion. The dough is soft and this will stop it from stretching
Place the 9 rolls into the lined baking pan. Cover with a damp tea towel and place in the oven on defrost setting (or a warm, draught-free spot) for 1½ hours
Preheat oven to 165 celsius fan-forced (if you've been using the oven to rise the dough, remove it before preheating!)
Bake rolls for 25 minutes, until golden brown
Once cooked, remove from oven and make the vanilla bean glaze