The panino con gubana is the sweet outlier in a catalogue of salume and cheese. Gubana is a Friulian dessert from the valleys around Cividale del Friuli: a sweet leavened dough rolled up around a dense paste of walnuts, raisins, pine nuts, candied peel, sugar, and a hit of grappa, then coiled into a tight spiral and baked so the cut face shows ring after ring of dark filling. Treating it as a panino means using it the way it is actually eaten in the hand, a thick slice or a split piece carrying its own filling, which makes it a sandwich by behaviour rather than by recipe. The defining fact is that this is a pastry, not a roll, and the sweetness is the entire reason it exists.
The craft was finished at the oven, and what matters at the eating end is the spiral and the ratio. The dough is enriched and proved so it bakes soft rather than bready, thin enough that the coiled filling, not the crumb, is most of each slice; rolled badly the spiral loosens and the nut paste falls out the moment it is cut. The filling is worked dense and bound so it holds the coil and reads as one dark seam through the slice rather than a loose crumble, the grappa cutting the sweetness of the raisin and candied peel. It is eaten at room temperature, often with a small glass of the same grappa or a sweet wine, when the dough is softest and the nut paste has settled. Nothing is added, because a gubana is a complete thing and a spread would only gild it.
The variations stay Friulian and few, each its own preparation rather than a line here: the rolled baked gubana itself, the related short-pastry gubanetti and the fried strucchi with the same nut filling, and the broader Germanic-northeast habit of holiday sweet breads, which is the Alto Adige and Friuli shelf and its own piece. Each is the same nut-and-grappa filling given a different dough, and each deserves its own article rather than being crowded in here.