Break half of the biscuits into not-too-small pieces.
Put the other half in a bag and bash them until you get finer crumbs, but don't reduce them to powder.
Combine everything in a large bowl.

In a second bowl, cream the soft butter at room temperature with the condensed milk until you have a smooth cream.

Sieve the unsweetened cocoa powder and gradually incorporate it into the butter and milk mixture, stirring until uniform.

Melt the dark chocolate in a bain-marie and, while still warm, add it to the cream. Stir carefully.

Pour the resulting cream into the bowl with the biscuits and mix using circular motions, without crushing, until you have a homogeneous mixture.

Lay out a sheet of cling film about 50 cm long, distribute the mixture to form a cylinder, and roll up the film, shaping the salami.
Close the ends like a sweet wrapper.

Refrigerate for at least 3 hours, until completely firm.

Once ready, remove the cling film, dust with icing sugar if desired, cut into 1.5–2 cm thick slices, and serve.