Mix the base dough
Combine flour, milk, active starter, eggs and sugar until no dry flour remains. Cover and rest 30 minutes.
Time: 30 minAdd salt and butter
Add the salt, then work in the softened butter gradually. Knead until the dough becomes smooth, elastic and able to hold tension.
Build strength
During the early bulk fermentation, complete 3–4 gentle folds about 30 minutes apart if the dough still needs strength.
Time: 30 minBulk ferment
Continue bulk fermentation until the dough is airy and roughly 60–75% larger. In a moderate room this may take about 4–6 hours, but follow the dough.
Time: 4–6 hrMake the filling
Mix 85 g softened butter, 180 g brown sugar, 15 g cinnamon and 5 g vanilla into a spreadable filling.
Roll and shape
Roll the dough into a rectangle, spread the filling evenly and roll it into a tight log. Cut into 8 large buns and arrange in a buttered baking dish.
Cold proof
Cover and refrigerate for 8–16 hours.
Time: 8–16 hrFinal proof
Bring the buns to room temperature and proof until visibly puffy and a light finger press returns slowly, usually about 1½–2½ hours depending on temperature.
Time: 1½–2½ hrBake
Bake at 350°F / 177°C for about 25–30 minutes, until richly golden and the center buns are fully baked, around 205–210°F internally.
Time: 25–30 minMake the frosting
Beat cream cheese, 55 g butter, 120 g powdered sugar and 5 g vanilla until smooth. Keep it cream-cheese-forward rather than overly sweet.
Finish
Let the buns cool slightly, then spread the frosting over the warm buns so it softens without disappearing completely.