01 - In a large bowl, whisk together the bread flour, fine sea salt, and instant yeast until evenly mixed.
02 - Add lukewarm water and 2 tablespoons extra-virgin olive oil to the dry mixture. Mix with a wooden spoon or spatula until you obtain a sticky, shaggy dough.
03 - Cover the bowl tightly with plastic wrap or a lid. Allow the dough to rise at room temperature for 8 to 18 hours until it has doubled in size and appears bubbly.
04 - Generously oil a 13x9-inch baking pan using olive oil. Pour the risen dough into the pan and gently stretch and press to fit the shape of the pan.
05 - Cover the pan loosely and let the dough rise for 1 to 2 hours, until puffy and expanded.
06 - Preheat the oven to 425°F.
07 - Drizzle 3 tablespoons olive oil across the dough surface. With oiled fingers, press deeply to create dimples over the entire dough.
08 - Sprinkle flaky sea salt and fresh rosemary leaves over the dough, if using.
09 - Bake in the preheated oven for 22 to 25 minutes until golden brown and crisp around the edges.
10 - Cool in the pan for 10 minutes, then transfer to a wire rack. Slice and serve warm or at room temperature.