In a large mixing bowl, combine 3 cups of bread flour, 1.5 cups of lukewarm filtered water, and 1 cup of active sourdough starter. Stir until just incorporated, cover, and let rest for 30 minutes.

After the autolyse, sprinkle 1.5 teaspoons of fine sea salt evenly over the dough and knead until fully integrated.

Over the next two hours, perform the stretch and fold technique every 30 minutes.

Spread half a cup of basil pesto over the dough, followed by one cup of grated parmesan cheese. Fold the dough to encase the fillings.

Transfer the dough to a floured banneton or bowl, cover, and refrigerate for 12-14 hours.

Preheat your oven to 475°F (245°C) with a Dutch oven inside. Flip the dough onto parchment, score it, and bake covered for 20 minutes, then uncovered for 25 minutes.

After baking, cool on a wire rack for at least 30 minutes before slicing.