A viper is a biscia, and this big one, or biscione, is a Christmas speciality of Reggio Emilia, made from almonds, sugar, egg whites and Sassolino, then topped with a meringue and canditi to make the face.
Why a snake for Christmas? Apparently a local pastry shop, the Pasticceria Nazzani in Reggio Emilia, made it one year and it just caught on. It is a play on the name of a similar Northern Italian sweet known in Milan (bissòlo), Vercelli (bissolano), Piacenza (bisolàn), Parma (busilàn), and Venice (bossolà).
Also known as biscione reggiano or biscione natalizio.
In Umbria, they make a similar spiral-shaped Christmas cake called a torciglione that resembles an eel.
Image by travel carnet