8 hours before starting the dough, feed your sourdough starter in a 1:1:1 ratio (I suggest doing 50g starter, 50g flour, 50g water).

In a large bowl, mix together the levain (fed sourdough starter), filtered water, bread flour, pumpkin puree, brown sugar, salt, and pumpkin pie spice using a danish dough whisk until the dough is smooth and all of the ingredients are mixed together (make sure there are no dry bits).

Over a total of 2 hours, perform 4 sets of stretch and folds every 30 minutes.

To perform the stretch and folds, lightly wet your hand. Reach down to the bottom of the bowl and pull the edges of the dough towards the center. Each time, turn the bowl ¼ turn and repeat. Cover and set aside. Repeat the stretch and folds every 30 minutes, for 2 hours, completing 4 stretch and folds total.

After the final stretch and fold, cover the dough and let it rise for another 3-4 hours, until doubled in size and there are bubbles on the surface.

Turn the dough onto a lightly floured surface, and stretch it into a large rectangle as thin as you can without tearing it. Sprinkle cinnamon all over the surface of the dough. Perform a letter fold by folding the dough into thirds like a letter, and rolling it up into a ball. Then, cover the dough and rest for 15 minutes. After 15 minutes, uncover the dough and do your final shaping by stretching the dough out as much as you can into a rectangle again, without tearing it. Sprinkle more cinnamon on the surface, and then perform a letter fold and roll it up into a ball.

Create tension in the dough by using your hands to push and pull the dough across your counter surface, creating a seam at the bottom.

Then, place the dough in a floured proofing basket, cover, and place in the fridge overnight or up to 3 days.

The next day, preheat the oven and dutch oven at 480F for 1 hour.

Invert the sourdough loaf on a piece of parchment paper, dust with flour and smooth it out. Use a very sharp knife or bread lame to score the bread.

Place the bread with the parchment paper into the dutch oven and place 3-4 ice cubes under the parchment paper. Place the lid back on top.

Bake at 480F for 20 minutes with the lid on, and with a baking sheet placed on the rack below the dutch oven. Then, reduce the oven temperature to 450F, remove the lid, and continue to bake for another 20 minutes.

Once done, remove from the dutch oven immediately. Let it sit for 30 minutes - 1 hour before slicing. Serve warm with butter and flaky sea salt.