Pane frattau is the Sardinian sandwich that has quietly become a lasagne and is still eaten by hand. The bread is pane carasau, the brittle parchment-thin Sardinian flatbread, baked twice until it is a crisp sheet that snaps. Here it is not split and filled but layered: a sheet is briefly softened in hot water or broth, laid down, spread with tomato sauce and grated pecorino, then another softened sheet over it, and the stack is built up two or three layers deep. A poached egg is set on top to finish. The result sits between a sandwich and a baked pasta, and the defining fact is that the crisp bread is deliberately turned soft and structural rather than kept as a wrapper.
The craft is the dip and the layering. Each sheet of carasau is passed through hot liquid for seconds only, just long enough to go pliable, because a sheet left too long dissolves into the sauce and the stack loses its definition. The tomato is a simple cooked sauce, loose enough to soak the bread but not so thin it floods the plate; the pecorino is grated between every layer so the salt and the sharp sheep's-milk note run through the whole height rather than sitting on top. The egg is poached soft so its yolk breaks down into the warm stack and binds the top layer. It is assembled and eaten straight away, while the layers still hold their separate identities and before the whole thing settles into one wet mass.
The variations stay in Sardinia and stay close to the layered idea: the version finished with a ladle of broth rather than plain water for a richer base, the one with a dusting of more pecorino under the egg, the simpler tomato-and-bread stack without the egg at all. Its crisp sibling, the same carasau brushed with oil and salt and left brittle, is pane guttiau. Each of those is a different treatment of the same Sardinian sheet, and each deserves its own article rather than being crowded in here.