In a large mixing bowl, combine the warm water and ripe sourdough starter. Stir gently to incorporate.
Add the pumpkin puree to the mixture, blending well until smooth.
In a separate bowl, mix the bread flour, salt, brown sugar, cinnamon, nutmeg, ginger, and cloves.
Gradually add the dry ingredients to the wet ingredients, mixing with your hands or a dough scraper until a shaggy dough forms.
Knead the dough on a floured surface for about 8-10 minutes until it is smooth and elastic.
Place the kneaded dough into a lightly greased bowl, cover with a kitchen towel, and let it rise at room temperature for about 4-6 hours, or until it has doubled in size.
Once risen, gently deflate the dough and shape it into a round loaf or place it into a proofing basket.
Cover the shaped dough with a towel and let it proof for an additional 1-2 hours.
Preheat your oven to 450°F (232°C) during the last 30 minutes of proofing.
If using a Dutch oven, place it in the oven to preheat. Otherwise, line a baking sheet with parchment paper.
Carefully transfer the dough to the preheated Dutch oven or place it on the parchment-lined baking sheet.
If desired, score the top of the dough with a sharp knife for decorative effect.
Bake for 30 minutes with the lid on (if using a Dutch oven) and then remove the lid and bake for an additional 15 minutes until the crust is golden brown.
Allow the bread to cool on a wire rack for at least 30 minutes before slicing.