Step 1

Add all the ingredients to a small mixing bowl and stir to combine. Cover and proof in a warm spot (around 78°F/26°C) for 5 hours or until the levain has doubled/tripled in size.

Step 2

3.5 hours after you prepared the levain: To a large mixing bowl, add the flour and cold water. Mix to combine using your hands or a rubber spatula. Cover the bowl and autolyse/rest for 1.5 hours.

Step 3

After 1.5 hours, add the levain to the main dough and mix by hand or with a stand mixer (with dough hook attachment) for 3-4 minutes. Add salt, and continue mixing for 2 minutes or until you can't feel any noticeable salt in the dough. Next, add about half of the olive oil, mix for 2 minutes, add the rest, and mix for 2-3 minutes until the dough is smooth.

Step 4

Place the dough in a clean, lightly oiled bowl. Proof the dough for 5 hours at around 75°F/24°C. Coil fold the dough every 30 minutes for the first 2 hours, then leave it alone to proof for the remaining 3 hours.

Step 5

After 5 hours, the dough should have nearly doubled in size. Transfer it to the fridge to cold-proof overnight (or up to 24 hours).

Step 6

Take the dough out of the fridge and dump it in an oiled/lined small baking pan or cast iron pan (12x8 inches/30x20cm)

Step 7

Gently stretch the dough to flatten it out in the pan. It doesn't matter if the dough isn't covering the whole pan yet, as long as it's somewhat even throughout (think of shaping a pizza).

Step 8

Cover the baking pan and proof at 75°F/24°C-78°F/26°C until doubled in size. The second proof typically takes 2-3 hours, but look less on the clock and more on how the dough looks.

Step 9

Preheat your oven to 500°F/260°C 30-45 minutes before you plan to bake the focaccia.

Step 10

When the focaccia has doubled in size: drizzle a generous amount of olive oil over the dough's surface. Use your fingers to poke dents all over the dough. Sprinkle on fresh rosemary, cherry tomatoes, and flaky salt on top.

Step 11

Bake for 18-20 minutes, until deep golden brown. Remove from the oven and let it cool for about 15 minutes before serving.