In a large mixing bowl, combine the active sourdough starter, pumpkin puree, and lukewarm water. Stir until well blended.
Add the bread flour, whole wheat flour, brown sugar, cinnamon, nutmeg, cloves, and ginger to the pumpkin mixture. Mix until a rough dough forms.
Add the salt and knead the dough on a lightly floured surface for about 10 minutes until smooth and elastic.
Place the dough in a lightly oiled bowl, cover with a damp cloth or plastic wrap, and let it rest at room temperature for 4 hours, folding the dough every hour to develop gluten.
After the bulk fermentation, shape the dough into a tight round loaf and place it seam-side up in a floured banneton or a bowl lined with a floured kitchen towel.
Cover and refrigerate the dough overnight (8-12 hours) for the final proof.
Preheat the oven to 450°F (230°C) with a Dutch oven or baking stone inside.
Carefully transfer the dough onto parchment paper, score the top with a sharp knife or razor blade, and place it into the preheated Dutch oven or directly on the baking stone.
Cover with the lid (if using a Dutch oven) and bake for 20 minutes.
Remove the lid and bake for an additional 25 minutes or until the crust is deep golden brown and the internal temperature reaches 205°F (96°C).
Remove the bread from the oven and cool completely on a wire rack before slicing.