3 cups all-purpose flour
1 packet (2 ¼ tsp) instant yeast
1 teaspoon salt
2 cups warm water
½ cup olive oil, divided, plus more for drizzling at the end
¾ cup fresh or frozen Oregon blackberries
1 tablespoon chopped fresh rosemary
In a large mixing bowl, whisk together the flour, yeast, and salt, then make a well in the middle and pour in the water and 2 tablespoons of the olive oil. Stir with a rubber spatula until thoroughly combined and a sort of doughy mass has formed. The dough will be messy and shaggy, but don’t worry — you’re not going to knead it.
Cover the bowl and leave it on the counter for 30-60 minutes, until it’s a little puffy, and use the spatula to fold the edges into the center to make more of a cohesive, less-shaggy ball-shaped mass. Cover again and set aside for 8 hours or overnight. If it’s warm in your kitchen, you can stash it in the refrigerator until the next day. It doesn’t really matter! After 8-12 hours, the dough will look more like very bubbly, puffy batter.
When you’re ready to bake, pour half of the remaining olive oil into a rimmed baking sheet or two round cake pans. Using a flexible dough scraper or rubber spatula, scrape the dough into your baking sheet or cake pans and let it proof again for another 2-3 hours, during which time it should slowly spread out to the edges of the pan(s).
In the last 20 minutes of the second proof, move a rack to the middle position of your oven and preheat to 475°. Pour the remaining olive oil over the top of the dough and, with clean fingers, gently press dimples into the top of the dough. You can press all the way down to the pan if you want. You’ll start seeing more bubbles form.
Sprinkle the blackberries over the top of the dough and add a few generous pinches of flaky sea salt. Bake until puffy and golden brown, about 20-25 minutes.
After you remove the focaccia from the oven, slide it out onto a cooling rack, sprinkle on the rosemary, and drizzle on more olive oil (this is where you can use the nice stuff). Let it cool for 10 minutes and then serve. Leftovers can be stored for 3-4 days in an airtight container; if you like, you can reheat for a couple minutes at 350°.