Preheat oven to 350°F and make sure oven rack is in the center of oven.
Take your chopped almonds, hazelnuts and biscotti and spread them out in an even layer on a baking sheet.
Place in oven and toast for 5-7 minutes, or until lightly toasted.
Remove from oven and let cool completely.
Set a heatproof bowl over a saucepan of simmering water and add chopped chocolate to the top bowl. Stirring frequently, cook until completely melted and smooth, then stir in orange zest, vanilla and rum. Remove from heat and set aside.
In a large bowl, beat together the butter and eggs until smooth, 3-5 minutes. Mix in cocoa powder and coffee to the egg mixture until no lumps remain, then whisk in melted chocolate mixture.
Stir until combined and gently fold in toasted nuts and biscotti.
Cover with plastic wrap and refrigerate for 1-2 hours, or until pliable.
Unwrap chocolate and turn it out onto a clean sheet of plastic wrap. Use your hands to roll chocolate into a long, 2-inch thick log. (Or 2 smaller logs.)
Tightly wrap log in plastic wrap, twisting (or tying) the ends so that it keeps its shape, and return to refrigerator for at least 4 hours, or overnight.
When ready to serve, use a sharp, serrated knife to cut 1/2-inch thick rounds.