Every region has its own recipe for blood sausage. Many are similar to that of Valle d'Aosta, where they call it boudin like its French cousin. In Liguria it's berodo or berodi, with pine nuts added. In Campania and the Basilicata, nu sanguanatu might even have bitter chocolate. In Friuli it's sanganel, and mixed with lardo. In Sicily it's sangeli.
Chocolate and pig's blood do seem to go together. In the south, especially in Basilicata where it's designated PAT, there's a sweet version, or sanguinaccio dolce, a kind of fudge made with bitter chocolate, coffee, cloves and sometimes cream, and spread on bread. It's a treat made for carnival, though these days, it's usually without the blood.
Images by: Alpha