1. In a large bowl whisk together sourdough starter, milk, egg, and sugar until combined.

2. Add flour and salt, mix until a rough dough forms, then let rest 30 minutes for autolyse.

3. Knead in softened butter a few cubes at a time until the dough is smooth, soft, and elastic, about 8–10 minutes by hand.

4. Place dough in an oiled bowl, cover and bulk ferment at room temperature for 4–6 hours until it rises by 50%, then refrigerate overnight.

5. Mix melted butter, brown sugar, cinnamon, and optional nutmeg or cardamom to make the filling.

6. Roll chilled dough into a 12 x 16 inch rectangle, spread filling evenly, then roll up tightly into a log.

7. Slice the log lengthwise, twist the two halves with cut sides up and place in a parchment-lined loaf pan.

8. Cover and proof at room temperature for 3–4 hours until visibly puffy.

9. Preheat oven to 180C (350F), brush loaf with milk or egg wash and bake 35–40 minutes until top is deep amber and internal temperature is 93C.

10. Brush the warm loaf with simple syrup (sugar and water mixture with vanilla), cool in pan 10 minutes, then transfer to a rack before slicing and serving.