FOR THE SPONGE
1 teaspoon / 4 grams active dry yeast
½ cup / 120 ml lukewarm water
1 tablespoon / 15 g organic sugar
Scant 3/4 cup /90 grams unbleached all-purpose flour
FOR THE DOUGH
1 teaspoon / 4 grams active dry yeast
1 cup / 240 ml lukewarm water
2 tablespoons / 30 grams organic sugar
3 tablespoons extra-virgin olive oil
¾ cup plus 1 tablespoon / 100 grams unbleached all-purpose flour
½ cup / 60 grams fine cornmeal
2 cups / 250 grams whole wheat flour or durum flour
1 ¾ teaspoons/ 12 grams fine sea salt
FOR THE TOPPING
2 teaspoons chopped fresh rosemary
2 tablespoons extra-virgin olive oil
¼ cup / 35 grams hazelnuts, skinned and halved (see note)
1 pound mixed fresh figs and plums, figs quartered, plums pitted and sliced in wedges
1 tablespoon / 15 grams organic sugar
¼ teaspoon ground cinnamon
Make the sponge. Combine yeast and water in a large bowl or the bowl of a stand mixer and stir to dissolve. Whisk in sugar and flour. Cover with plastic wrap and let rise in a warm place until bubbly and doubled in volume, about 45 minutes.
Make the dough. If using a stand mixer, whisk together yeast and water in a small bowl and let stand until creamy, a few minutes. Add to the sponge in the mixer bowl, along with sugar and olive oil. Add flours (including cornmeal) and salt and mix in with the paddle attachment for 1 to 2 minutes, until ingredients are amalgamated. Change to dough hook and knead on medium speed for 8 to 10 minutes. The dough should come together and slap against the sides of the bowl. It will be slightly tacky. To make the dough by hand, combine yeast and water as directed and whisk into sponge with sugar and olive oil. Whisk in all-purpose flour. Add salt, cornmeal and remaining flour, one cup at a time, folding it in with a spatula or a wooden spoon. When you can scrape out the dough, add flour to the work surface, put dough on top and knead for 8 to 10 minutes, until soft and velvety. Return to bowl (coat bowl lightly with olive oil first).
Cover bowl tightly with plastic wrap and let dough rise in a warm spot until doubled, about 1 1/2 hours.
Shape the focaccia. Coat a 12-x-17-inch sheet pan (sides and bottom) with olive oil. Line with parchment and flip parchment over so the exposed side is oiled. Turn dough onto baking sheet. Oil or moisten your hands and press out dough until it just about covers the bottom of the pan. Dough may be sticky. Cover with a towel and allow it to relax for 10 minutes, then continue to press it out until it reaches the edges of the pan. Cover with a damp towel and let rise in a warm spot for 45 minutes to an hour, or until dough is full of air bubbles.
Preheat oven to 425 degrees after 15 minutes of rising (30 minutes before you wish to bake), preferably with a baking stone in it. Combine chopped rosemary and olive oil for the topping in a small pan and heat just until rosemary begins to sizzle. Count to 30 and remove from heat. Swirl olive oil in the pan and pour into a small measuring cup or ramekin. Allow to cool.
With lightly oiled fingertips or with your knuckles, dimple the dough, pressing down hard so you leave indentations. Place hazelnut halves in the indentations. Distribute the fruit evenly over the dough and drizzle on the oil and rosemary. Combine the remaining tablespoon of sugar and the cinnamon, and sprinkle evenly over the fruit and dough.
Place pan in oven on baking stone. Spray oven 3 times with water during the first 10 minutes, and bake 20 to 25 minutes, until edges are crisp and the top is golden. If you wish, remove the focaccia from the pan and bake directly on the stone during the last 10 minutes. Remove from oven, remove from pan at once and cool on a rack. If you want a softer focaccia, cover with a towel when you remove it from the oven. Serve warm or at room temperature.