In a stand mixer bowl, combine all dough ingredients.

Mix with the dough hook on low speed until the ingredients are incorporated. Increase the speed to medium-low and mix for 2-3 minutes until a cohesive dough forms.

With wet hands, stretch one side of the dough upwards and fold it toward the center. Rotate the bowl 90 degrees and repeat on each side for a total of four sets of stretch and folds.

Drizzle about 1 tablespoon of olive oil over the top of the dough and cover the bowl tightly with plastic wrap or a damp kitchen towel. Let the dough rise in a warm spot for 1-2 hours, until it doubles in size.

Coat a 9×13 inch baking pan with about 2 tablespoons of olive oil.

Transfer the dough to the prepared pan. With clean, oiled hands, gently press and stretch the dough to reach the corners of the pan. If the dough resists stretching, let it rest for 5-10 minutes and try again.

Drizzle 2-3 tablespoons of olive oil over the surface, and then use your fingertips to create deep dimples all over the dough. Press firmly but gently to create little pockets where the oil will gather.

Cover and allow to rise for an additional 1-2 hours, until almost doubled in size.

Drizzle an additional 2 tablespoons of olive oil over the surface, and then create deep dimples with your fingertips. Sprinkle rosemary and flaky salt over it (if using).

Preheat your oven to 425°F with the rack in the middle position.

Bake for 25-30 minutes until golden brown and its internal temperature reaches 200°F.

Optional: For an extra crispy crust, place a pan with 1 cup of hot water on the bottom rack during baking.

Remove the bread from the oven. Optional: Brush it with an additional tablespoon of olive oil for a softer crust.

Let the bread cool in the pan for about 10 minutes before slicing.

Slice your sourdough discard focaccia bread and enjoy! It’s perfect on its own, with olive oil for dipping, or alongside a meal.