Preheat your oven to 400°F (200°C). Place the halved garlic head on a piece of aluminum foil, drizzle with a tablespoon of olive oil, and wrap it tightly. Roast for about 30-35 minutes, until the cloves are soft and golden. Allow it to cool slightly before squeezing the roasted garlic into a bowl. Mash it with a fork until smooth.
In a large mixing bowl, combine the warm water and active dry yeast. Let it sit for about 5-10 minutes until foamy. Next, stir in the roasted garlic, remaining olive oil, and fine grain sea salt.
Gradually add the white flour to the mixture, stirring until a shaggy dough forms. The dough will be sticky, which is normal for focaccia.
Turn the dough onto a floured surface and knead for about 5-7 minutes until it becomes smooth and elastic. Alternatively, use a stand mixer with a dough hook for about 4 minutes on medium speed.
Place the dough in a greased bowl, cover it with plastic wrap or a kitchen towel, and let it rise in a warm place for about 1-2 hours, or until doubled in size.
Gently punch the dough down to release the air. Transfer the dough to a greased baking sheet and stretch it out to fit the pan, using your fingers to create dimples all over the surface.
Cover the dough again and let it rise for another 30-45 minutes. During this time, preheat your oven to 425°F (220°C).
After the second rise, drizzle the top of the focaccia with olive oil, sprinkle with fresh rosemary, and finish with flaky sea salt. Bake for 20-25 minutes, or until golden brown.
Remove the focaccia from the oven and let it cool slightly on a wire rack. Slice and serve warm, or let it cool completely for later enjoyment.
