1. Feed and refresh the sourdough starter 4–6 hours before baking and allow it to peak.

2. In a mixing bowl combine starter, warm milk, eggs, sugar, and half of the flour until smooth.

3. Add softened butter and remaining flour, kneading until the dough is elastic and smooth, about 8–10 minutes by mixer or 15 minutes by hand.

4. Transfer dough to a greased bowl, cover, and let rise in a warm place until doubled, about 4–6 hours.

5. Meanwhile, melt butter for the filling and stir in brown sugar, cinnamon, and a pinch of salt to form a paste.

6. Roll the rested dough into a 12×16 inch rectangle and spread the cinnamon filling evenly, leaving a small border.

7. Roll the dough into a log, cut lengthwise, and twist the two strands with cut sides up.

8. Place the twisted loaf into a lined 9×5 inch pan, cover, and proof until puffy, about 3–5 hours.

9. Preheat oven to 375°F and brush the loaf with egg wash or milk.

10. Bake for 35–40 minutes until golden and an internal temperature of 190°F is reached.

11. Brush the hot loaf with simple syrup and cool in the pan for 15 minutes before transferring to a wire rack.