Combine the flour, starter, milk, egg and sugar in the bowl of a stand mixer. Mix until a shaggy dough forms, then rest for 20 minutes.
Add the softened butter and salt and knead for 8–10 minutes until smooth, elastic and silky.
Transfer to a lightly greased bowl, cover and leave to ferment somewhere warm until soft, puffy and increased by around 60–75%. This should take approximately 2½–4 hours depending on the strength of your starter and room temperature.
Meanwhile, make the filling. Place the brown sugar and orange zest in a bowl and rub together with your fingertips until fragrant.
Brown the butter in a small saucepan over medium heat until nutty and golden. Remove from the heat and immediately stir through the cardamom and half the cinnamon. Leave to infuse for 5 minutes.
Pour the brown butter mixture into the orange sugar and add the remaining cinnamon and salt. Stir until combined into a spreadable paste.
Lightly butter a 24–26cm round baking dish.
Turn the dough onto a lightly floured surface and roll into a rectangle approximately 35 x 45cm. Spread the filling evenly over the dough, taking it right to the edges.
Roll tightly from the long side into a log, then slice into 8–10 scrolls.
Arrange the scrolls in the prepared baking dish. Cover and proof somewhere warm until noticeably puffy and touching, around 1½–3 hours depending on temperature.
Just before baking, stir together the cream and brown sugar and drizzle between the scrolls.
Bake at 180°C fan for 35–45 minutes, or until deeply golden and cooked through in the centre. If the tops begin browning too quickly, loosely cover with foil for the final part of baking.
Allow the scrolls to cool for 10–15 minutes.
To make the glaze, whisk together the icing sugar, maple syrup, milk and flaky salt until smooth. Drizzle generously over the warm scrolls and serve.