Direction :

1. Make the focaccia: In a large bowl, whisk together the flour, salt, and instant yeast. Add the water. Using a rubber spatula, mix until the water is absorbed and the ingredients form a sticky dough ball.
2. Cover the bowl with a tea towel or plastic wrap and set inside your refrigerator.
3. The following morning (or 8 to 10 hours later), remove the bowl from the fridge. Line a rimmed sheet pan with parchment paper or coat with nonstick cooking spray. Pour 3 tablespoons oil on the sheet pan. Using two forks, deflate the dough by releasing it from the sides of the bowl and pulling it toward the center. Rotate the bowl in quarter turns as you deflate, turning the mass into a rough ball. Use the forks to lift the dough onto the prepared sheet pan. Roll the dough ball in the oil to coat it all over. Let it rest without touching it for 2 to 4 hours (depending on the temperature of your kitchen).
4. Set a rack in the middle of the oven and preheat it to 425°F. Drizzle the remaining tablespoon of oil over the surface of the dough. With lightly greased hands, press down on the dough, using all 10 fingers to dimple and gently stretch the dough outward. Pull gently on the ends and stretch them toward the corners of the sheet pan. When the dough begins to resist being stretched, let it rest for 5 minutes, then stretch it again, continuing until it fits most of the sheet pan.
5.  Dimple lightly again. Sprinkle all over with sea salt. Transfer the sheet pan to the oven and bake for 20 to 25 minutes, until the underside is golden and crisp. Remove the pan from the oven, and transfer the focaccia to a cooling rack. Let it cool for at least an hour before cutting.
6. To cut the focaccia for the slab sandwich, trim off the very outer edges—this exposes the crumb, which makes it easier to halve. I like to start the halving process by cutting through each corner, then running the serrated knife through the short end until I get to the midway point, then starting from the other short end until I get to the midway point. A sharp, serrated knife is helpful. Try to keep your knife as parallel to the bread as possible, and I find if I hug the top layer as opposed to aiming for the center, I get a more even cut.
7. Make the Egg Sandwich. Preheat the oven to 425ºF. Lay the bacon on a sheet pan. You will likely have to overlap pieces and lay pieces on top of one another to start, but don’t worry, they will shrink. Cook 10 minutes, remove pan from oven, and, using forks, spread out/separate the slices of bacon. Return pan to the oven, and cook for 10 to 15 more minutes or until the slices are looking crispy. Remove pan from the oven and transfer crisp slices to a paper-towel lined plate. If necessary, drain off some of the fat, and return the pan to the oven one last time to crisp up the remaining pieces. Transfer bacon to plate.
8. Turn oven off to let it cool down faster. You can leave the door open, too, to expedite the cooling. You need it to be at 300ºF. Grease a half sheet pan (I use a cheap, nonstick Baker’s Secret sheet pan purchased from a grocery store—it measures 11×16.5 inches) very well with butter. Crack all 12 eggs in a big bowl, add salt and pepper and the splash of cream, then whisk until well combined. Add the chives, and gently fold until mixed. Pour the mixture into the prepared pan. Sprinkle with cheese evenly. Bake until the eggs are just set, about 15 minutes.
9. Transfer the bottom half of the focaccia slab onto a cutting board. When the eggs have cooked, use an offset spatula to loosen them from the pan, then transfer to the bread. Trim off any excess, overhanging eggs. Lay the bacon on top. Scatter the lettuce on top. Top with the top half of bread. Cut the sandwich into 12 pieces (2 cuts through the short end; 3 cuts through the long end). Serve with hot sauce, mayonnaise and any other condiments you like.