Our focaccia has a moist but airy crumb sandwiched between thin but ultra-crunchy top and bottom crusts, thanks to a generous amount of olive oil in the pan and on top of the dough. If you don’t already have a standard 18x13" half sheet pan, we recommend getting one for this recipe so you have just the right proportion of crumb to crust. Make sure the pan is very clean before you start; otherwise, the dough might have a tendency to stick during baking.