In a large bowl, whisk together the flour, salt, and instant yeast. Add the water and mix until a sticky dough forms. Cover and let rest for 30 minutes.

Rub the surface of the dough with olive oil. Cover the bowl and place it in the refrigerator for at least 12 hours or up to 3 days.

Prepare the baking pans by either lining them with parchment paper or greasing them with butter.

Pour a tablespoon of oil into each prepared pan. Deflate the dough and split it into two equal pieces. Place each piece in a pan and roll to coat in oil. Let them rest for 3 to 4 hours at room temperature.

Preheat the oven to 425?F. Sprinkle rosemary over the dough (if using) and oil the tops. Use fingers to create dimples in the dough and sprinkle with flaky sea salt.

Bake for 25 to 30 minutes until the underside is golden and crisp. Cool for 10 minutes before serving.