1. Combine the Wet Ingredients: In a large mixing bowl, gently combine your active sourdough starter with the warm water. Stir until the starter is mostly dissolved. This ensures even distribution of the starter throughout the dough.

2. Add Dry Ingredients (Except Raisins): To the starter mixture, add the granulated sugar, salt, bread flour, and ground cinnamon. Mix with a wooden spoon or your hands until a shaggy dough forms and no dry spots of flour remain. The dough will be sticky at this stage.

3. Incorporate the Raisins: Turn the dough out onto a lightly floured surface. Gently knead for about 5 minutes, then flatten the dough slightly and sprinkle the raisins over the surface. Fold the dough over itself and continue to knead for another 2-3 minutes until the raisins are evenly distributed. Be careful not to over-knead, as this can tear the raisins.

4. First Rise (Bulk Fermentation): Place the dough back into the large, lightly oiled bowl. Cover the bowl with plastic wrap or a damp kitchen towel. Let it rise at room temperature (around 70-75 F) for 8-12 hours, or until it has nearly doubled in size and looks bubbly. This long, slow rise develops the sourdough’s characteristic flavor.

5. Shape the Loaf and Second Rise (Proofing): Gently turn the dough out onto a lightly floured surface. Shape it into a round or oval loaf. If you have a banneton basket, dust it with flour and place the dough seam-side up. Otherwise, place it seam-side down on a piece of parchment paper. Cover loosely with plastic wrap and let it proof for another 2-4 hours at room temperature, or until it looks puffy and springs back slowly when gently poked.

6. Preheat Dutch Oven and Bake: About 30 minutes before baking, place your Dutch oven with its lid into your oven and preheat to 450 F (230 C). Carefully remove the hot Dutch oven. If using parchment paper, lift the dough by the paper and carefully lower it into the hot Dutch oven. Score the top of the dough with a sharp knife or razor blade (a simple cross or a few parallel lines work well).

7. Bake Covered and Uncovered: Cover the Dutch oven with its lid and bake for 30 minutes. Remove the lid and continue to bake for another 15-25 minutes, or until the crust is deeply golden brown and the internal temperature reaches 200-210 F (93-99 C).

8. Cool Completely: Carefully remove the bread from the Dutch oven and transfer it to a wire rack. Let it cool completely for at least 1-2 hours before slicing. Slicing too early can result in a gummy texture. If desired, brush the warm loaf with melted butter for a softer crust and added flavor.