In a bowl, combine the starter, pumpkin, warm water, and salt, then whisk until smooth.
Gradually add the bread flour and mix until a dough forms.
Allow the dough to rest for one hour.
After resting, perform four rounds of stretch and folds to develop the dough's structure.
Mix in brown sugar, cinnamon, and pumpkin pie spice into the dough.
Shape the dough into a swirl.
Form the loaf and let it proof.
After a 12-hour cold retard, bake the loaf.
