The panino con pecorino di fossa is the pit-aged reading of the sheep cheese, and the pit is the entire sandwich. Pecorino di fossa is matured by burying the wrapped cheeses in tufa pits lined with straw, sealed, and left to ferment underground in the airless dark of the Marche and Romagna hills. What comes out is unlike any cellar or cave pecorino: the paste is amber, crumbly, sometimes faintly oily, and carries a powerful earthy, fermented, almost truffled funk with a sharp note that lingers. That underground ferment is what defines this panino. The bread is a plain crusted roll, there only to carry the cheese, because a fossa at full strength is one of the loudest things in the Italian dairy and a strong loaf would be a second argument it does not need.
The craft is respecting the funk and matching a counter to it. The pit-aged paste is dry and friable, so it is broken into rough crumbs rather than cut in clean slices, each crumb releasing the earthy ferment as it dissolves. The flavour is so dominant that the only sane partners are sweet ones that frame the funk instead of fighting it: the classic is a spoon of honey or saba, the Romagnola grape must syrup, whose dark sweetness rounds the sharp fermented edge and turns the cheese from challenging to balanced. No oil and no savoury sauce, because the fossa is already pungent and oily at the edge and a savoury addition only muddies it. The bread carries; the crumb and the sweet counter are the whole composition.
The named directions stay in the fossa country of the Montefeltro and Romagna. There is the version eaten plain with piadina and honey, the pairing with a sweet wine for the same balancing logic, and the milder cow-and-sheep blended pit cheeses that read softer. The Abruzzo mountain pecorino and the cave-aged Filiano are different cheeses entirely and are not this. Each of these is its own preparation, and each deserves its own article rather than being crowded in here.