1. Mixing the Dough (Autolyse and Initial Mix): In a large bowl, combine the warm water and active sourdough starter, stirring gently until the starter is mostly dissolved. Add the bread flour and mix with a Danish dough whisk or your hands until no dry spots remain. This will be a shaggy, sticky dough. Cover the bowl with a damp towel or plastic wrap and let it rest for 30 minutes to 1 hour (this is the autolyse stage, which helps hydrate the flour). After the autolyse, sprinkle the salt over the dough and gently work it in by squeezing and folding the dough for about 2-3 minutes.

2. Incorporating the Parmesan Cheese: Spread the dough out slightly on a clean work surface. Sprinkle the grated Parmesan cheese evenly over the surface of the dough. Gently fold the dough over itself several times, ensuring the cheese is well distributed throughout. You want the cheese to be integrated but not completely mashed into the dough.

3. Bulk Fermentation with Stretch and Folds: Return the dough to the bowl. Over the next 4-6 hours (or until the dough has increased in volume by about 30-50% and is bubbly), perform a series of “stretch and folds.” Every 30-45 minutes during the first 2-3 hours, gently grab a portion of the dough from one side, stretch it upwards, and fold it over to the opposite side. Rotate the bowl and repeat this 3-4 times until all sides have been stretched and folded. This builds strength in the dough. After the first few hours, let the dough rest for longer periods.

4. Shaping the Loaf: Lightly flour your work surface. Gently turn the dough out onto the surface. Carefully pre-shape the dough into a loose ball or rectangle, letting it rest for 20 minutes to relax the gluten. Then, proceed with your final shaping technique (e.g., a boule or a batard). You want to create tension on the surface of the dough.

5. Cold Proofing: Place the shaped dough seam-side up into a floured banneton or a bowl lined with a floured kitchen towel. Cover it tightly with plastic wrap or place it in a large plastic bag to prevent drying. Refrigerate for 8-12 hours, or up to 24 hours. Cold proofing develops flavor and makes the dough easier to handle.

6. Baking the Sourdough: Preheat your oven to 500 F (260 C) with a Dutch oven inside for at least 30 minutes. Carefully remove the hot Dutch oven. Gently invert the cold dough into the hot Dutch oven. Score the top of the dough with a sharp razor blade or lame. Place the lid back on the Dutch oven and bake for 20 minutes.

7. Finishing the Bake: After 20 minutes, remove the lid from the Dutch oven. Reduce the oven temperature to 450 F (230 C) and continue baking for another 20-25 minutes, or until the crust is deeply golden brown and the internal temperature reaches 200-210 F (93-99 C).

8. Cooling the Bread: Carefully remove the bread from the Dutch oven and place it on a wire rack to cool completely for at least 1-2 hours before slicing. This is crucial for the crumb structure and flavor to set.