1. 1. Activate the Yeast and Combine Wet Ingredients: In a large mixing bowl, combine the warm water and active dry yeast. Stir gently and let it sit for 5 minutes until the yeast becomes foamy. This indicates it’s active. Then, add your active sourdough starter, salt, and olive oil to the bowl. Stir everything together until well combined.

2. 2. Mix in Flour and Parmesan: Gradually add the all-purpose flour, one cup at a time, mixing with a wooden spoon or a stand mixer with a dough hook until a shaggy dough forms. Once most of the flour is incorporated, add 3/4 cup of the grated Parmesan cheese and the chopped rosemary (if using). Continue to mix until the dough comes together and pulls away from the sides of the bowl.

3. 3. Knead the Dough: Turn the dough out onto a lightly floured surface. Knead for 8-10 minutes until the dough is smooth and elastic. It should spring back when gently poked. If using a stand mixer, knead on medium speed for about 6-8 minutes.

4. 4. First Rise (Bulk Fermentation): Lightly grease a clean large bowl with olive oil. Place the kneaded dough into the bowl, turning it once to coat the top. Cover the bowl with plastic wrap or a clean kitchen towel and let it rise in a warm place for 2-3 hours, or until doubled in size. The exact time will depend on the temperature of your kitchen and the activity of your starter.

5. 5. Shape the Loaf and Second Rise: Gently punch down the risen dough to release the air. Turn it out onto a lightly floured surface and shape it into a round or oval loaf. Place the shaped loaf on a baking sheet lined with parchment paper. Sprinkle the remaining 1/4 cup of Parmesan cheese over the top of the loaf. Cover loosely with plastic wrap or a clean towel and let it rise again for 30-45 minutes, or until noticeably puffy.

6. 6. Preheat Oven and Bake: While the dough is on its second rise, preheat your oven to 400 F (200 C). Once the oven is preheated and the loaf has risen, place the baking sheet in the oven. Bake for 30-35 minutes, or until the crust is golden brown and the internal temperature reaches 200-210 F (93-99 C) when checked with an instant-read thermometer.

7. 7. Cool Before Slicing: Once baked, remove the bread from the oven and transfer it to a wire rack to cool completely before slicing. This is crucial for the texture and flavor to fully develop.