1. In a bowl mix sourdough starter, water, and pumpkin puree until combined

2. Whisk flour, salt, brown sugar, and cinnamon in a large bowl

3. Pour wet mixture into dry ingredients and mix until no dry flour remains

4. Cover and autolyse for 45 minutes

5. After autolyse gently fold in swirl brown sugar and cinnamon

6. Perform stretch and folds every 30 minutes for 2 hours during bulk fermentation

7. Pre-shape the dough, rest 20 minutes, then shape into a boule or oval

8. Place shaped dough seam side up in a floured banneton and refrigerate overnight

9. Preheat oven with Dutch oven to 450°F (232°C) for 30 minutes

10. Transfer chilled dough to parchment, score the top, and place in hot Dutch oven

11. Cover and bake 20 minutes, then uncover and bake 20–25 minutes until crust is deep golden

12. Cool on a wire rack for at least 1 hour

13. Mix granulated sugar and coating cinnamon and sprinkle lightly over warm crust