A quintessential fall sourdough loaf! This one has lots of pumpkin flavor, a really soft texture, and the perfect orange hue thanks to a can of pumpkin puree. The ribbon of cinnamon brown sugar throughout adds the perfect sweetness.I like to bake these in loaf pans since swirl bread doesn't always have the best structure to it. Covering the loaf pan with a second, inverted loaf pan creates the perfect amount of steam. If you don't have 4 metal loaf pans, you will need to do this in batches.Makes 2 loaves.
Mix: In a large bowl, combine the water, starter, and pumpkin puree. Add the flour and salt and mix until fully combined. Scrape down the sides of the bowl and cover.Stretch and folds + first rise: Over the next 2-3 hours, do 3-4 rounds of stretch and folds, working your way around the bowl each time. The dough will change drastically as you do this! Let the dough rise until doubled in size, about 6 hours more.Shape: Turn the dough out onto a lightly floured surface. Divide in half and shape each half into a round. Cover with a tea towel and allow to rest for 20-30 minutes - this is an optional step but will make the dough stretch more easily.Meanwhile, combine the brown sugar and cinnamon.Take one of the pieces of dough and press into a rectangle on a lightly floured surface. Stretch it with your hands and dimple it with your fingertips to shape it into a roughly 8 by 12 (up to a 8 by 16-inch) rectangle. Keep in mind the longer your rectangle is, the more intricate your swirl will be. Sprinkle the top of the dough with half of the cinnamon sugar mixture, leaving a strip uncovered on both the longer edges and one of the shorter edges. Beginning opposite the uncovered short edge, roll the dough into a tight log. Pinch to seal the edge once you've reached the other side, and pinch to seal each end.Second rise: Place seam side up in an oblong proofing basket or a loaf pan lined with a floured tea towel. Repeat with the second piece of dough.Cover and let rise for 30 minutes to 1 hour, until slightly puffed up and the dough bounces back slowly if you press on it. Be careful not to stretch the second rise too long with this bread - the sugar will liquefy and seep out of the bread.Toward the end of the second rise, preheat the oven to 450 degrees. Grease two 9 by 5-inch loaf pans.Bake: Turn each loaf out onto a piece of parchment paper. Score each one with three long, slightly shallow slices (going too deep here can affect the swirl). Transfer to the prepared loaf pans using the parchment paper. Cover each with an inverted loaf pan - this will create the perfect amount of steam. Bake for 30 minutes covered, then uncover and bake an additional 20 minutes, until a thermometer inserted into the middle of the loaf reads at least 200 degrees.Let the loaves cool for a few minutes in the pan, then invert to release. Cool completely on a wire rack.Storage: This bread is best in the first 2 days, but is good toasted a few days beyond that. If you still have some around after that, I highly recommend making French toast and/or croutons!