01 -
Combine sourdough starter, lukewarm water, and sugar in a jar. Stir until dissolved, add flour, and mix to a stiff, dough-like consistency. Knead briefly for smoothness, cover loosely, and let rise at 27–30 °C for about 4 hours until doubled, airy, and fragrant.
02 -
In a stand mixer with paddle attachment, combine all of the active leaven, sugar, egg, and milk. Mix at medium-high speed until smooth then switch to dough hook. Add bread flour and mix on low speed until fully incorporated. Cover and rest dough for 30 minutes at room temperature, allowing hydration.
03 -
Add salt to dough and knead for a few minutes. Gradually add softened butter cubes while mixing on low speed, ensuring each piece is incorporated. Increase speed to medium and knead for 15 minutes until dough is smooth, glossy, and releases from the bowl sides.
04 -
Transfer dough to a lightly greased bowl, cover with plastic wrap, and ferment at 26–28 °C for approximately 4 hours until many small air bubbles form. Refrigerate overnight for cold fermentation.
05 -
Melt butter in a small pot over medium heat. Add milk, sugar, honey, rum, and cinnamon; bring to a boil. Stir in ground poppy seeds, remove from heat, cover, and allow to soak for 15 minutes. Cool the mixture to room temperature.
06 -
Allow dough to return to room temperature. On a floured surface, roll dough into a 30 × 50 cm rectangle. Spread cooled poppy seed filling evenly, leaving a border. Roll up tightly from a short side into a log. Using a sharp knife, slice the log lengthwise in half.
07 -
Line a 23 × 13 cm loaf pan with parchment paper. Twist the two dough strands together, crossing from the center outwards. Lift shaped dough into prepared pan.
08 -
Cover pan loosely with plastic wrap and proof in a warm environment (30 °C) for about 4 hours, or until the dough rises above the rim of the pan.
09 -
Preheat oven to 180 °C. Brush dough surface with beaten egg. Bake for 40–50 minutes until golden brown and an internal temperature of at least 83 °C is reached. Cool babka in the pan for 10 minutes before transferring to a rack to cool completely.