The panino con Casciotta d'Urbino is a Marche cheese sandwich whose whole character comes from a blend most table cheeses do not attempt: roughly three parts sheep's milk to one part cow's. That ratio is the point. The sheep's milk gives the Casciotta a soft, slightly sweet, faintly grassy body; the cow's milk rounds off the sharpness the sheep would carry alone, leaving a mild, supple, pale cheese that yields under a thumb and tastes gentle rather than assertive. It is a protected denomination from the hills around Urbino, and the sandwich is the simplest way to read it: one cheese, the right bread, and the discipline to add nothing that would speak over something this quiet.
The craft is matching a mild, yielding cheese to a bread that will not bully it. Casciotta is young and soft, so it is sliced thick rather than shaved, because a translucent shaving of a delicate cheese disappears entirely and the point is to taste it in a clear layer. The bread is plain and not too strongly crusted, often a piece of the local pane, since an aggressive sourdough or a heavily salted loaf would flatten the cheese's faint sweetness. Almost nothing is added: at most a thread of oil or a little soft bread to carry it, never a sharp pickle or a strong cured meat that would turn the Casciotta into a background note. It is eaten at cool room temperature, where the cheese reads softest and the sheep's-milk sweetness is most legible.
The variations are gentle and mostly about pairing rather than altering the cheese. There is the plain build of nothing but bread and a thick slice; there is the version met with fresh fava beans or a little honey, the sweet against the mild working the way it does across the Italian cheese counter. Other Marche and central-Italian sheep and mixed-milk cheeses follow their own logic and their own pairings, and each of those deserves its own article rather than being crowded in here.