In the bowl of a stand mixer using the dough hook, mix together the flour, butter and sugar (if using) for 2 -3 minutes.
Add in the sourdough discard, banana puree, milk and vanilla extract. Knead for 10 minutes on medium speed. The dough should be smooth and stretchy at this point.
Transfer the dough to a lightly greased bowl and cover with a damp cloth. Leave for 6-8 hours (maximum of 8 hours) at room temperature or until doubled in size.
Punch down the risen dough and tranfer to a lightly floured work surface. Now, roll the dough out into a rough rectanglular shape - doesn't have to be perfect.
Using a pastry brush, spread your cinnamon roll filling (see instructions below) and layer on some sliced dried figs (optional).
Use both hands to roll the dough into a log, then cut 2-3cm wide pieces off the log to form little rolls. Arrange into a baking dish and leave to proof in the fridge for an hour before baking.
Bake at 180°C for 30-35 minutes or until groden brown.