Whole Wheat Focaccia with Cherry Tomatoes and Olives

Make the sponge. Combine yeast and water in a large bowl or the bowl of a stand mixer and stir to dissolve. Whisk in flour. Cover with plastic wrap and let proof 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 sponge in the mixer bowl, along with olive oil. Add flours and salt and mix in with the paddle attachment for 1 to 2 minutes, until ingredients are amalgamated. Change to the dough hook and knead on medium speed for 8 to 10 minutes. 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 the olive oil. Whisk in all-purpose flour. Add salt 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 the dough on top and knead for 8 to 10 minutes, until soft and velvety. Return to the 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 the parchment over so exposed side is oiled. Turn dough onto the 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 30 minutes of rising (30 minutes before you wish to bake), preferably with a baking stone in it. Place thyme and olive oil for the topping in a small saucepan or skillet and heat until thyme begins to sizzle. Count to 30 and remove from heat. Swirl the oil in the pan, then transfer to a measuring cup or ramekin and allow to cool. With lightly oiled fingertips or with your knuckles, dimple the dough, pressing down hard so that you leave indentations. Arrange cherry tomato halves and olives on dough, pressing them into the dimples. Drizzle on olive oil and use your fingers to distribute any thyme that remains in the cup or ramekin over the tomatoes. Sprinkle with a little coarse sea salt if desired. Place pan in oven on baking stone. Spray oven 3 times with water during the first 10 minutes of baking and bake 20 to 25 minutes, until edges are crisp and top is golden. If you wish, remove 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. Sprinkle torn or slivered basil leaves over the surface of the focaccia. Serve warm or at room temperature.