Lay out a cake or tart form with aluminum foil. Toast all the nuts in the oven or pan, and be sure to remove all the pistachio shells. Be careful not to burn them, toast them just enough to release their aroma and slightly caramelize them.
Crush the finished nuts coarsely along with the biscuits - not into crumbs, but small pieces. In a water bath, heat the condensed milk with the butter and once warmed, add the crushed chocolate. Stir until everything is homogenized and you get a smooth chocolate mixture.
Remove it from the heat and add the vanilla extract and liqueur (you can substitute it with rum). Add the nuts and biscuits and carefully pour the mixture into the prepared form. Smooth the top and leave it at room temperature until cooled well for several hours.
Then remove it from the form and put it in the fridge to tighten well for at least 1 day. You can also leave it in the fridge for a few days or even in the freezer, but be sure to wrap it in aluminum foil.
Before serving, leave it at room temperature for several hours and cut it into pieces.