1. Put yeast and water into the bowl of a mixer; stir to dissolve. Add oil and sugar. Stir in 1 1/2 tablespoons salt, then flour, 1 cup at a time, until dough comes together. Attach bowl to mixer fitted with the dough hook. Mix until smooth, about 2 minutes. Let rest in bowl, loosely covered with a damp towel, 20 minutes.

2. Return dough to mixer; mix until it is smooth, about 5 minutes. Transfer dough to a large oiled bowl. Refrigerate, loosely covered, at least 6 hours or overnight.

3. Remove dough from the refrigerator; let dough stand until it comes to room temperature, about 1 1/2 hours. Place a pizza stone or baking sheet in cold oven.

4. Preheat oven to 500 degrees. Divide the dough into 4 pieces. On a lightly floured work surface, gently stretch each piece into an 8-inch round; brush with oil. Sprinkle garlic and rosemary over tops; season with salt and pepper. Drizzle with oil.

5. Dust a pizza peel or baking sheet with cornmeal. Place 1 flatbread on peel; slide onto pizza stone. Repeat with remaining pieces. Bake until golden brown, about 10 minutes. Garnish with rosemary. Sprinkle with salt. Drizzle with oil.