Roast the garlic (can be made a day or two in advance):

Preheat over 400 degrees F. Remove any loose papery exterior skin from the head of garlic. Cut off the top of the head to expose the cloves, about ½ inch typically. Place the head of garlic in the center of a sheet of aluminum foil large enough to wrap up the garlic.  Drizzle with olive oil and sprinkle with salt.  Wrap up the foil tightly and place in a small ovenproof bowl (in case the foil leaks).  Bake in the oven until the garlic is soft, about 50 minutes.  Remove from oven and cool to room temperature. Leave at room temperature if using immediately or refrigerate until ready to use. 

Make the dough:

In a large bowl (large enough to accommodate the dough at least doubling in bulk), stir together the flour, yeast and salt until combined.  Add in olive oil and 2 cups of the lukewarm water. Using a wooden spoon or your hands, mix until the dough starts to come together.  If too dry, continue to add lukewarm water, 1/4 cup at a time, until the dough forms a ball. (I needed ½ cup extra.) 

Dump the dough onto a lightly floured surface and using your hands, knead the dough until it is smooth, about 5 minutes.  Clean the large bowl and drizzle a few tablespoons of olive oil in the bottom.  Add the dough to the bowl and turn to coat in oil (your hands work the best here). Cover tightly with plastic wrap and place in a warm spot to rise. Let rise until doubled in size, 3 to 4 hours. (Don’t panic if it takes longer – timing will depend on your room temperature.) 

Spread 3 tablespoons olive oil evenly onto an 18 x 13-inch rimmed baking sheet. Transfer the dough to the pan using your hands. Give the dough a turn to coat it in oil. Using the flat palm of your hand and your fingers, gently stretch the dough to the edges of the sheet pan.  The dough will try to shrink back a bit as you are doing this so continue to stretch until it reaches the edges.  Cover tightly again with plastic wrap and let stand at room temperature for another 45 minutes to an hour to allow it to rise until light. 

Bake the focaccia:

Preheat oven to 450 degrees F.

Using your fingertips, dimple the entire top of the focaccia. Pop the roasted garlic cloves from the roasted head and break up into smaller pieces using either your fingers or a knife.  Scatter the roasted garlic over the surface of the dough, gently pressing (or smearing if soft) the cloves into the dough. Drizzle the entire surface with a few tablespoons of extra-virgin olive oil.  Sprinkle with flaky sea salt.  

Bake until golden brown, 20-30 minutes. Remove from oven and let rest for 5 minutes.  Release focaccia from the pan using a metal spatula. Transfer to a cooling rack.  Allow to cool slightly, slice and serve immediately. Or allow to cool to room temperature, slice and serve. Enjoy!