The night before you plan to bake the bread, prepare the dough.
In a large mixing bowl, combine the warm water with the active dry yeast, and allow the mixture to sit for five minutes while you weigh out the remaining dry ingredients.
Add the 260 grams of bread flower, 320 grams of all-purpose flour, 3 tsp of ground cinnamon, 1 tsp of ground ginger, 15 grams of kosher salt, 140 grams of sourdough starter, 25 grams of white granulated sugar, and 50 grams of brown sugar.
Stir with a spoon until no visible clumps of flour remain.
Cover the bowl with a large plastic bag or plastic wrap, and allow the dough to proof at room temperature for 30 minutes.
After the dough has sat for 30 minutes, wet your hands thoroughly before folding the dough on top of itself in the bowl a few times.
After you have folded the dough and helped to shape it in the bowl, allow it to rest at room temperature, covered with plastic wrap again, for an additional 30 minutes.
After the dough has rested for a second time, remove the plastic wrap.
Add the softened butter, drained raisins, chopped pecans, and chopped walnuts to the top surface of the dough.
Use your fingers to push the ingredients into the dough, trying your best to evenly distribute the nuts and fruit and butter throughout the dough.
Carefully fold the dough a few times on top of itself to help incorporate the raisins and nuts and butter.
Dump the mixture out onto a lightly floured work surface.
If making two loaves, cut the dough in half.
Shape each individual piece of dough into a dough ball, and lightly flour the round top of each dough ball with rice flour.
*Rice flour will help reduce the likelihood that your dough ball will stick to the bowl that it proofs in overnight.
Prepare your two batonnets or proofing bowls by dusting them with some rice flour.
Place the dough balls with the rounded top-side facing down into the proofing bowls or batonnets, and cover with plastic bags.
Place each covered dough ball in the fridge, and allow them to rest in fridge overnight.
Before you bake the bread the next morning, preheat your oven to 500F.
Add your Dutch oven to the preheating oven, so that it gets very hot.
*I use a cast iron version of a Dutch oven that was fairly cheap and will last forever.
When the Dutch oven has preheated for roughly 30 minutes, remove it from the oven and remove the lid.
Carefully invert your first loaf of bread into the base of the Dutch oven, so that the rounded section is now facing up.
Place the lid back on the Dutch oven, and place the bread into the oven.
Bake the bread for 30 minutes with the lid on at 500F.
*Baking for the first 30 minutes with the lid on enables the bread to steam, which encourages the loaf to rise during the early stages of the baking process.
After the bread has baked for 30 minutes, reduce the oven heat to 400F, remove the lid, and continue to bake for an additional 20 minutes with the lid off.