Focaccia col formaggio is the Ligurian name for a thing that barely resembles the dimpled, oily focaccia most people picture. There is no leavening and almost no crumb. Two sheets of dough, made from flour, water, oil, and salt, are stretched until they are nearly translucent, thin enough to read a hand through. A soft, sour, milky cheese, crescenza or stracchino, is dropped in irregular nuggets across the bottom sheet, the top sheet is laid over and the edges pinched to seal, and the whole thing is sent into a fierce oven on an oiled pan. It comes out in minutes, blistered into amber and white domes, the cheese inside molten and tangy, the dough crackling at the edges and tender where the filling kept it soft. It is closer to a filled cracker than to a bread.
The craft is in the stretch and the heat, and there is little margin in either. The dough has to be pulled to the edge of tearing, because a sheet left too thick bakes into something doughy and the contrast is lost, while a sheet pulled too far splits and the cheese escapes. The cheese has to be a fresh, fast-melting type that goes liquid before the thin dough can scorch, which is why a firmer cheese does not substitute cleanly. The pan is oiled rather than floured so the underside fries to a brittle gold while the top blisters. This is a sandwich measured in minutes from oven to hand: it wants eating almost immediately, when the cheese still pulls and the blisters still shatter, and it goes flat and chewy if it sits, which is why in Liguria it is sold by the cut straight off the tray.
The named versions of this idea are tightly clustered and geographically specific. The focaccia di Recco is the protected, regulated reference point, the version with a defined recipe and a name tied to its town. The focaccia di Recco con formaggio is the same thing stated with the cheese made explicit. Other towns along the Riviera bake near-identical sheets under their own names with small differences in cheese or oven. Those distinctions matter and they deserve their own articles rather than being crowded in here.