Mix together 6 grams ripe sourdough starter with 60 grams water and 60 grams flour. Cover and let sit overnight at 78ºF until doubled in size, bubbly and active.

Mix together ripe, bubbly, active levain with water, granulated sugar, salt, lemon zest and bread flour. Mix together with a dough whisk or spoon until a sticky dough forms. Cover with plastic wrap or a bowl cover and let rest for 30 minutes.

Take the cover off the dough and perform 4-6 coil folds. The dough will be very sticky for this first set of coil folds but will strengthen over time. Wet your hands with water. Place your hands under the middle of the dough and pull up. The dough will stretch up (but should not tear) and release from the bottom of the bowl. Once the dough releases, let the dough fall back under itself. Repeat the process for both sides of dough. Then turn the container and repeat the coil fold. Cover and let rest for 30 minutes.

Wet your hands. You will notice the dough is stronger than your first set of folds. Repeat the coil folds, noticing how the dough is changing and strengthening over time. Cover and rest for 30 minutes.

Add 125 grams of blueberries on top of the dough. Wet your hands. Perform 3-4 coil folds, incorporating the blueberries as you fold. Cover and rest for 30 minutes.

Repeat the last set of coil folds, continuing to incorporate the fresh blueberries.

Cover and rest the dough at 78ºF for 2.5-3 hours until the dough has risen about 50-60% in the bowl.

After the long bulk rest, line a 12-inch round or 9 by 13 metal baking pan with parchment paper. Pour 50 grams light-flavored olive oil in the pan. Tip the pan around to coat the entire bottom of the parchment paper.

Dump the focaccia dough into the pan and spread out with your fingers without tearing the dough as best you can. It's okay if the dough doesn't completely spread out yet, as it rises, you will be able to stretch it a little more.

Let the dough sit in a warm 78-80ºF place for 2-3 hours until doubled in size, puffed up and very airy.

Add softened butter, brown sugar, flour and salt to a small bowl. Use your fingers or a spoon to stir together until a thick crumb topping is formed. Set aside.

After the dough is puffed up, jiggly and aerated with air bubbles, gently spread the dough out to fill the edges of the pan. Pour 30 grams of melted butter on top of the dough. Sprinkle the crumb topping all over the top of the risen dough. Add the remaining 50 grams of fresh blueberries spread out over the top of the dough. Take your fingers and gently dimple the dough.

Pre-heat the oven to 425ºF. Once the oven is pre-heated, bake the focaccia for 25-30 minutes until bubbly, crispy and light golden brown on top and the baked focaccia registers 200ºF. Let cool in the pan for 5-10 minutes before removing to a wire rack.

While the focaccia is baking, mix together the lemon glaze. Whisk powdered sugar, lemon juice, vanilla extract and salt together. Drizzle over the warm focaccia.