The focaccia di Noli is the focaccia of a small fishing town on the Ligurian Riviera, and what marks it out is its restraint relative to the standard Genovese round. Noli's version runs leaner and more austere: a thinner disc, a drier crumb, less of the heavy surface oil that defines the focaccia of Genoa, and a more pronounced salt-and-crust character. The dough is still pressed into a tray and dimpled, still brushed with a salt brine, but the whole thing is built closer to a plain baked flatbread than to the oil-laden Genovese style. The difference is local and deliberate, the kind of small divergence one stretch of coast holds onto for its own reasons.
As a sandwich base the leaner build changes the logic. With less surface oil and a drier crumb, the noli does not saturate the way a Genovese round does, so it carries a moist filling better and stays firmer in the hand over a longer afternoon. The trade is that it depends more on its salt and its crust for flavor, since there is less oil doing that work, which is why a noli baked without enough salt or enough color on the crust tastes thin. The thinner disc also means it sets quickly and holds less heat at the center, so it rewards being eaten soon after baking, warm and plain or split with a simple cured meat or a wedge of local cheese, the way a coastal town eats the bread it makes daily rather than something assembled for an occasion.
The named relatives along this coast are each a small adjustment of the same idea. The plain Genovese round is the oilier, softer reference point. The focaccia di Voltri pushes in the opposite direction, thinner and crisper still. The focaccia col formaggio of the same region is the unleavened, cheese-sealed outlier that shares only a name. Each is its own subject and deserves its own article rather than being crowded in here.