• Mix starter, flour, water, and brown sugar in a bowl.
• Cover and ferment at room temp for 6-8 hours until bubbly and doubled.
• In a mixer bowl, add: flour, cornstarch, sweet starter, eggs, milk, salt, and sugar.
• Mix on medium until a rough dough forms (about 3-5 min).
• Add softened butter gradually and knead for another 8-10 min until elastic and smooth.
• Cover and proof at room temp for 4–6 hrs, or overnight in the fridge.
• Warm cream until steaming.
• Pour over chopped chocolate and let sit 1 min.
• Stir until smooth, then mix in cocoa powder, sugar, butter, vanilla, and chopped nuts.
• Let cool to room temp before spreading.
• Roll the dough into a rectangle (~9x15 in).
• Spread filling evenly, leaving ½ in border.
• Roll into a tight log and slice lengthwise.
• Twist the two halves into a spiral, cut side up.
• Place in a greased loaf pan. Cover and proof 2-4 hrs.
• Preheat oven to 175°C (350°F).
• Bake for 35-40 min until golden brown and a skewer comes out clean.
• Tent with foil if browning too fast.
• While baking, heat sugar and water in a saucepan until dissolved.
• Brush syrup over hot babka right out of the oven.
• Let cool completely before slicing.

Rest Time (Optional)

• Chill overnight after first proof (8-12 hrs) for enhanced flavor and easier shaping.