1) Place 1 slice of mortadella at a time on the cutting board and remove the four circular bezels (which you can use for other preparations, such as meatballs or fillings), in order to obtain 4 squares. Cut each square into 3 strips of equal size. Roll up the 12 strips in a cylinder shape, secure them with a toothpick and put in the fridge.
2) Transfer the cheese to a bowl and add 2 tablespoons of grated Parmesan cheese and ground pepper. Work it with a fork (or use a food processor if you prefer), in order to get a very smooth cream. Close the bowl with cling film and place in the refrigerator. Wrap the pistachios in a sheet of parchment paper and chop them roughly with the meat mallet.
3) Fill the mortadella cylinders with the cheese cream, helping yourself with a pastry bag and sprinkle with pistachios. Drizzle the balsamic glaze on the plates, arrange the mortadella rolls on top, remove the toothpicks and serve.