Mix the dough: Mix the starter, pumpkin purée, water, and maple syrup. Add the flour, salt, pumpkin pie spice, and cinnamon. Mix until no dry flour remains. Cover and rest for 30 minutes.
Stretch + folds: Complete 3-4 sets of stretch-and-folds, about 30 minutes apart. (1 1/2-2 hours total here)
Bulk ferment: Let the dough continue fermenting until it looks somewhat puffy, has some bubbles, and has risen about 50%. This will typically take another 3–6 hours, depending on the temperature of your kitchen.
Make the cinnamon swirl: Combine the sugar, cinnamon, flour, and pinch of salt.
Shape and add the swirl: Gently stretch the dough into a rectangle.Sprinkle half of the cinnamon mixture evenly over the dough. Fold the sides inward, then sprinkle on the remaining cinnamon mixture.Roll and shape into a loaf. Cold proof: Place seam-side up in a banneton or oiled bowl. Cover and refrigerate 8–14 hours.
Bake the bread: Preheat your Dutch oven at 450°F for at least 30 minutes.Turn out and score the cold loaf.Bake covered at 450°F for 27 minutes.Remove the lid and reduce the temperature to 425°F. Bake another 18–22 minutes uncovered, until deeply golden. The internal temperature should reach about 200°Cool completely before slicing.