In the bowl of your stand mixer fitted with the paddle attachment, combine the flour, salt, yeast, dried ground rosemary and pepper. Stir in the warm water, and 2 tablespoons of the olive oil. Add the grated Parmesan, and mix for 1 minute on low speed until well combined.If you don't have a stand mixer, you can simply mix the dough by hand, vigorously for 1 minute with a spoon or a Danish dough whisk.
Spray a 9x13 inch baking dish with non-stick baking spray, then drizzle 2 tablespoons of olive oil in the pan, tilting the pan so the oil coats the bottom of the pan.
Scrape the dough into the pan. Cover the pan tightly with plastic wrap, then set it in a warm place to rise until the dough fills the pan, about 60-90 minutes. If you gently shake the pan, the dough should be very jiggly.
Drizzle the top of the dough with the remaining 1/4 cup olive oil, then use your fingers to very gently dimple the dough. The dough may slightly deflate when you do this, but it shouldn't deflate excessively. Decorate the top of the focaccia with the fresh rosemary sprigs.
Preheat the oven to 400 F, and position a rack in the center of the oven. Bake the bread for 30 minutes, until a digital instant read thermometer inserted in the center reads 200 F. The bread will still be a pale golden color, but if you want more browning, you can turn on your broiler for a few minutes to brown the top.
Sprinkle the bread with the flaky finishing salt. Let cool for at least 15-20 minutes, then slice and enjoy warm.
Store leftover bread in an airtight container at room temperature for up to 3 days. To reheat, place pieces of bread in your toaster oven or convection oven, and reheat at 300 F for about 10 minutes, until hot and toasty.