Step 1

In the bowl of a stand mixer fitted with the hook attachment, whisk together the bread flour, 1 tablespoon of sea salt, and the instant yeast to combine.

Step 2

Pour in the water and 2 tablespoons of olive oil, and knead on medium speed for 5 minutes, or until the dough is smooth and elastic.

Step 3

Cover the bowl with plastic, and let it rise at room temperature for an hour and a half, or until the dough has doubled in size.

Step 4

Pour 2 tablespoons of olive oil into a 10-inch cast-iron skillet or round cake pan, and spread it over the entire surface and up the sides.

Step 5

Transfer the dough to the pan, and gently stretch it to fill the pan.

Step 6

Cover the pan with plastic, and let it rise at room temperature for an hour and a half, or again until the dough has doubled in size.

Step 7

Preheat the oven to 450 degrees Fahrenheit.

Step 8

Lightly dampen your fingers with water to prevent sticking, and press them into the dough to make dimples.

Step 9

Drizzle the remaining 1 tablespoon of olive oil over the top of the dough.

Step 10

Sprinkle the remaining ½ teaspoon of flaky sea salt and the rosemary evenly over the dough.

Step 11

Bake the focaccia for 25 to 30 minutes, or until the top is golden brown and the bottom is crisp.

Step 12

Let the focaccia cool in the pan for 5 minutes, then transfer it to a wire rack, and let it cool for at least 10 minutes before slicing.

Step 13

Serve the focaccia warm or at room temperature.