Centuries ago, focaccia began as a byproduct: When bakers needed to gauge the heat of the wood-fired oven — focaccia stems from focolare and means “fireplace” — they would tear off a swatch of dough, flatten it, drizzle it with olive oil, and pop it into the hearth to bake as an edible oven thermometer.
From there evolved countless variations on the theme — the stuffed pizzalike focaccia in Puglia and Calabria, the ring-shaped focaccia in Naples, focaccia made from rich or lean doughs, and even sweet versions. That said, it’s the dimpled, chewy, herb-topped deep-dish focaccia alla genovese that’s most fundamental.
As is traditional, our recipe starts with a sponge — a mixture of flour, yeast, and water that ferments for at least six hours before it’s added to the bulk dough. The sponge helped develop gluten (which gives breads structure and chew), depth of flavor, and a hint of tang.
Rather than knead the dough, we simply used a series of gentle folds, which developed the gluten structure further while also incorporating air for a tender interior crumb. (This method was also helpful because our dough was quite wet and therefore difficult to knead; the more hydrated a bread dough, the more open and bubbly its crumb — a characteristic we were looking for in focaccia — because steam bubbles form and expand more readily.)
