Instructions

• In a medium bowl, whisk together 2-1/2 cups warm water (110°F), 2-1/4 teaspoons yeast, and 1 tablespoon honey. Let sit 5 minutes, until foamy (active dry yeast will foam; instant yeast may foam less but this step is fine for either).
• Optional — make herbed oil (skip for plain focaccia): In a small saucepan combine 4 tablespoons of the olive oil, 2 teaspoons minced garlic, 1 tablespoon chopped fresh thyme (or 1 teaspoon dried), 1 tablespoon chopped fresh rosemary (or 1 teaspoon dried), and 1/4 teaspoon pepper. Warm gently over low heat 5–10 minutes until very fragrant. Remove from heat and let cool completely. Set aside the cooled herbed oil. If making plain focaccia, measure out 4 tablespoons plain olive oil and set aside. Reserve the remaining 2 tablespoons olive oil for later steps.
• In a large bowl, combine 5 cups all-purpose flour and 1 tablespoon salt. Add the yeast mixture and stir until a shaggy dough forms.
• Press the dough to one side of the bowl and pour in the 4 tablespoons of reserved oil (plain or cooled herbed). Using your hands (oiled or wet), pick up the sticky dough and turn it over twice so the surface is coated in oil.
• Cover the bowl tightly with plastic wrap and refrigerate 8–24 hours. (If you want to bake sooner, let the dough rise at room temperature until bubbly and wobbly, about 2–3 hours.)
• Remove 1 tablespoon of the 3 tablespoons unsalted butter from the refrigerator and rub it all over the bottom and sides of your baking pan (9×13-inch or 13×18-inch). Leave the pan at room temperature. Remove the dough from the fridge. Using two forks, gather the dough farthest from you, lift it up and fold it over toward the center, turn the bowl a quarter turn, and repeat until you have folded the dough 4 times total. Gently let the dough slide from the bowl into the prepared pan.
• Let the dough rise, uncovered, in a warm spot for 1.5–3 hours, until it is bubbly and wobbly and when poked it springs back slowly leaving an indentation.
• Preheat the oven to 450°F (230°C). Lightly oil your hands with about 1 teaspoon of the reserved olive oil and press/stretch the dough to fill the pan. Dimple the dough all over with your fingertips. Drizzle 1 tablespoon of the reserved olive oil evenly over the surface.
• Bake until the focaccia is puffed and deeply golden brown: 20–30 minutes for a 13×18-inch pan or 25–35 minutes for a 9×13-inch pan. Remove from the oven and let rest 10–15 minutes.
• Finish and serve: - For herbed focaccia: brush the top with the remaining 1 tablespoon of the reserved olive oil (use the cooled herbed oil if you made it). - For plain focaccia: melt the remaining 2 tablespoons unsalted butter and brush it over the warm bread; sprinkle flaky sea salt if desired. Cut into squares and serve warm (for sandwiches, slice each square in half).