Transfer sponge to the bowl of a stand mixer fitted with dough hook. Add bread flour, olive oil and salt. Mix together on low speed until dough forms, about 2 minutes. Increase speed to medium and knead for 6-8 minutes until dough is smooth and elastic.
Transfer dough to a large well oiled bowl. Cover. Set in a warm place to rest for about 45-60 minutes until dough has risen to double the size.
Starting at the outside, fold dough onto itself. Bring a piece of the outside and fold it inward, rotating bowl all the way around. Cover and let dough rest for another 15-20 minutes while you preheat oven.
Preheat oven to 400℉. Generously coat 9x13-inch baking pan with olive oil. Set aside.
Turn rested dough onto a well-floured work surface. Use the heel or palm of your hands to stretch dough out to roughly a 9x13-inch rectangle. Transfer dough to prepared baking pan. Cover and let dough rest for 40-60 minutes until dough is puffy and dough slowly springs back when poked.
Dimple surface of risen dough with fingers. Drizzle about 2 tablespoons olive oil over surface. Season with sea salt flakes or grated parmesan cheese. Bake for 25-30 minutes until dough is golden.
Let rest in pan for 10 minutes before serving. Serve warm or at room temperature. Slice in half to build sandwiches.