10:00 PM: In a small glass jar, mix your 10g of starter culture into 30g of water. Add 60g of bread flour and knead with your hands into a firm, tight ball. Roll it into a tight cylinder and drop it directly into a small jar filled with fresh room-temperature water.

Let it sit on your counter at 74–78°F (23–26°C) for 8 to 10 hours. The starter cylinder will absorb moisture, puff up, and float proudly to the top of the water.

8:00 AM – The Autolyse: In your stand mixer bowl, whisk the 100g of milk, 65g of sugar, 150g of pumpkin purée, 1 large egg, and the optional 0.5g of dry yeast together until smooth. Fish out your floating starter ball, extract exactly 65g of its soft interior core, and break it into pieces into the bowl. Dump all 325g of bread flour on top, mix until a shaggy mass forms with no dry streaks, cover, and let autolyse for 1 hour.

9:00 AM: Attach your dough hook attachment. Mix the dough on low speed for 2 to 3 minutes (or on speed 3 for a KitchenAid mixer) until it becomes cohesive. Add the 6g of salt and knead for 2 more minutes until a firm ball forms.

Add the 32g of soft butter. Turn your machine up to medium-high speed and knead continuously for 10 minutes until the fat incorporates seamlessly and the dough clears the sides of the bowl beautifully.

Cover the bowl and let bulk ferment for 3 to 5 hours at a warm 76–80°F (24–28°C). Perform 2 separate rounds of structural stretch-and-folds during this window until the dough looks light and slightly puffy.

Meanwhile, prepare the filling: In a small bowl, mix the 100g of brown sugar, 3 teaspoons of cinnamon, 1 teaspoon of pumpkin spice, 1 tablespoon of flour, and 60g of soft butter together until a smooth paste forms.

Dust your counter with flour and turn the dough out. Use a rolling pin to flatten it into a neat 9×17 inch rectangle. Spread your prepared pumpkin spice filling evenly across the entire surface all the way to the edges.

Starting from the long side, roll the sheet up tightly into a dense, long log. Place the log on a tray lined with parchment paper and slide it into the freezer for exactly 10 minutes to firm up the fats for clean slicing.

Line your loaf pan with parchment paper. Take the chilled log and use a sharp knife to slice it completely in half lengthwise, exposing all the beautiful interior spice layers.

Twist the two halves together tightly into a classic, woven braid. Transfer the braid into your pan, gently curling the ends under if it runs a bit too long. Cover loosely and let it proof for 3 to 4 hours at room temperature until the babka fully doubles in size.

Preheat your oven to 375°F (190°C). Slide the pan onto the middle rack and bake for 35 minutes until the woven crown turns a rich, uniform golden brown. Let cool completely on a wire rack.

Whisk the 1/2 cup of powdered sugar, 1 tablespoon of milk, and 1/4 teaspoon of pumpkin spice together in a small cup until smooth. Drizzle the glaze generously across the cooled babka before slicing.