Rosemary Focaccia

1. FOR THE SPONGE: Combine flour, water, and yeast in large bowl and stir with wooden spoon until uniform mass forms and no dry flour remains, about 1 minute. Cover bowl tightly with plastic wrap and let stand at room temperature at least 8 hours or up to 24 hours. Use immediately or store in refrigerator for up to 3 days (allow to stand at room temperature 30 minutes before proceeding with recipe).
2. FOR THE DOUGH: Stir flour, water, and yeast into sponge with wooden spoon until uniform mass forms and no dry flour remains, about 1 minute. Cover with plastic and let rise at room temperature for 15 minutes.
3. Sprinkle 2 teaspoons salt over dough; stir into dough until thoroughly incorporated, about 1 minute. Cover with plastic and let rise at room temperature for 30 minutes. Spray rubber spatula or bowl scraper with vegetable oil spray. Fold partially risen dough over itself by gently lifting and folding edge of dough toward middle. Turn bowl 90 degrees; fold again. Turn bowl and fold dough 6 more times (for total of 8 folds). Cover with plastic and let rise for 30 minutes. Repeat folding, turning, and rising 2 more times, for total of three 30-minute rises.
4. One hour before baking, adjust oven rack to upper-middle position, place baking stone on rack, and heat oven to 500 degrees. Gently transfer dough to lightly floured counter. Lightly dust top of dough with flour and divide it in half. Shape each piece of dough into 5-inch round by gently tucking under edges. Coat two 9-inch round cake pans with 2 tablespoons oil each. Sprinkle each pan with 1⁄2 teaspoon salt. Place round of dough in 1 pan, top side down; slide dough around pan to coat bottom and sides with oil, then flip dough over. Repeat with second piece of dough. Cover pans with plastic and let rest for 5 minutes.
5. Using fingertips, press dough out toward edges of pan, taking care not to tear it. (If dough resists stretching, let it relax for 5 to 10 minutes before trying to stretch it again.) Using dinner fork, poke entire surface of dough 25 to 30 times, popping any large bubbles. Sprinkle rosemary evenly over top of dough. Let dough rest in pans until slightly bubbly, 5 to 10 minutes.
6. Place pans on baking stone and lower oven temperature to 450 degrees. Bake until tops are golden brown, 25 to 28 minutes, rotating pans halfway through baking. Transfer pans to wire rack and let cool for 5 minutes. Remove loaves from pans and return to rack. Brush tops with any oil remaining in pans. Cool for 30 minutes before serving. (Leftover bread can be wrapped in double layer of plastic wrap and stored at room temperature for 2 days. Wrapped with additional layer of aluminum foil, bread can be frozen for up to 1 month.)

FOCACCIA WITH KALAMATA OLIVES AND ANCHOVIES
Omit salt from pans in step 4. Substitute 1 cup kalamata olives, pitted, rinsed, and chopped coarse, 4 rinsed and minced anchovy fillets, and 1 teaspoon red pepper flakes for rosemary. Sprinkle each focaccia with 1⁄4 cup finely grated Pecorino Romano as soon as it is removed from oven.

FOCACCIA WITH CARAMELIZED RED ONION, PANCETTA, AND OREGANO
Cook 4 ounces finely chopped pancetta in 12-inch skillet over medium heat, stirring occasionally, until most of fat has been rendered, about 10 minutes. Remove pancetta with slotted spoon and transfer to paper towel–lined plate. Add 1 chopped red onion and 2 tablespoons water to fat left in skillet and cook over medium heat, stirring often, until onion is soft and beginning to brown, about 12 minutes. Remove skillet from heat and set aside. Omit rosemary. After poking surface of dough rounds in step 5, sprinkle with pancetta, onion, and 2 teaspoons minced fresh oregano. Continue with recipe as directed.