10:00 PM – Levain Stabilization: In a clean glass jar, whisk the 7g of starter culture into 35g of water until loose. Stir in 35g of bread flour. Mix until smooth, cover loosely, and leave at a room temperature of 74–78°F (23–26°C) overnight for 8 to 10 hours until it triples in volume.

Sweet Potato Processing: Roast a fresh sweet potato in its skin until completely tender. Allow it to cool down to room temperature, peel off the skin, and mash the flesh smoothly with a fork or ricer to remove all lumps. Set aside for the morning.

8:00 AM – The Potato Autolyse: In your stand mixer bowl, combine all 125g of water, 300g of bread flour, 125g of your cooled mashed sweet potato, 9g of honey, and 60g of your active overnight levain (plus the optional 0.5g of dry yeast if using). Stir thoroughly with a heavy spoon until a shaggy, dense dough mass forms. Cover and let rest for 1 full hour to completely hydrate the starches and activate early gluten networks.

9:00 AM – Primary Gluten Mixing: Secure the bowl onto your stand mixer fitted with the dough hook. Mix on a low speed for 2 to 3 minutes (or KitchenAid speed 3 for 3 to 4 minutes) until a cohesive structure forms. Sprinkle in the 6g of fine sea salt and continue mixing for 2 more minutes until fully incorporated.

Fat Integration & Emulsification: Add the 30g of softened or melted butter. Raise the mixer speed to medium and knead continuously for 10 minutes. The high-fat matrix will gradually integrate, clearing the sides of the bowl completely to leave a smooth, pliable dough.

The Windowpane Verification: Wet your hands with water, pinch a portion of the dough, and stretch it gently upward. It should stretch into a translucent, paper-thin windowpane membrane without tearing, signaling proper gluten formation.

Bulk Proofing Window: Cover the bowl tightly and leave it to ferment at a warm room temperature for 3 to 4 hours. The dough should look visibly relaxed, light, and slightly puffy to the touch.

1:00 PM – Cold Fermentation Retard: Slide the entire covered container directly into your refrigerator to chill down the butter fats and stabilize the dough structures for 8 to 9 hours until the late evening.

10:00 PM – Loaf Shifting & Tension Roll: Remove the chilled, firm dough from your refrigerator and tip it cleanly onto a lightly floured work surface. Using a rolling pin or your hands, flatten and shape the dough into a tight, uniform log matching the exact length of your 9x5 loaf pan.

Pan Setup & Placement: Line the bottom of your 9x5 inch loaf pan with a sheet of parchment paper (lightly oiling the paper is recommended for a clean release). Place your shaped log seam-side down into the pan.

The Long Overnight Ambient Rise: Cover the loaf pan loosely with plastic wrap. Let it proof overnight on your kitchen counter for 7 to 9 hours at a stable room temperature around 76°F (24°C). By morning, the wild yeasts will have worked steadily, allowing the dough to double or rise slightly over the pan rim into an airy, light crown.

7:00 AM – The Morning Bake: Preheat your home oven to 375°F (190°C). Dust the top crown of your beautifully risen sweet potato loaf with a very light coating of flour for a rustic look.

Baking Cycle: Slide the pan onto the center rack of your oven and bake for 35 to 40 minutes until the top crust turns a uniform, rich golden brown. Carefully turn the bread out of the loaf pan onto a wire cooling rack and let it cool down entirely before slicing into sandwich portions.