In a mixing bowl, combine the active sourdough starter, water, and pumpkin puree. Mix well until smooth.

In a separate bowl, whisk together the all-purpose flour, salt, and spices (cinnamon, nutmeg, ginger, cloves).

Gradually add the dry ingredients to the pumpkin mixture, stirring until a shaggy dough forms. Use a dough scraper or spatula to incorporate all the flour.

Once combined, knead the dough for about 8-10 minutes until it becomes smooth and elastic. If it's too sticky, add a little more flour as needed.

Place the dough in a lightly greased bowl, cover it with a damp cloth or plastic wrap, and let it rise at room temperature for about 4-6 hours, or until doubled in size.

After the first rise, gently deflate the dough and shape it into a round loaf. Place it seam side up in a floured proofing basket or a bowl lined with a kitchen towel. Cover and let it rise for another 2-4 hours, or until puffy.

Preheat the oven to 450°F (232°C) about 30 minutes before baking. If using a baking stone, place it in the oven to heat up.

Once the dough has risen, carefully invert it onto a piece of parchment paper. Score the top with a sharp knife or bread lame.

Slide the dough (on the parchment) onto the hot baking stone or baking sheet. Bake for 30-40 minutes, or until the crust is golden brown and the internal temperature reaches 200°F (93°C).

Remove the bread from the oven and let it cool on a wire rack for at least 30 minutes before slicing.