Whisk the eggs with the sugar, add the melted chocolate and butter, and stir.
Sift in the flour with the salt and cocoa powder, and stir again - the chocolate batter is ready. Pour it into a rectangular pan lined with parchment.
For the creamy layer, whisk the egg with the sugar, add the mascarpone, and whip until smooth. Set aside 4 tbsp of this mixture and mix it with the currant jam to get two colors of batter.
Pour the creamy batter over the chocolate layer, spoon the berry batter on top, and use a skewer to create random marbled swirls.
Bake in an oven preheated to 160-170°C for 35-40 minutes. Let the finished bake cool completely, cut into squares - ready to enjoy!