Clean and slice carefully the mushrooms and spring onion. Seal the pork tenderloin in a pan with a little extra-virgin olive oil, about a couple of minutes per side. Remove the meat and deglaze the bottom of the pan with cognac. Add the butter, let it melt it and then add the spring onion and the Champignon mushrooms. Cook about 10 minutes over medium heat, stirring frequently, add salt and pepper and then cooking cream. Reduce the sauce a few minutes, cut the fillet into medallions and put it back in the pan with the sauce. Cook a couple of minutes stirring frequently, then turn off the heat and place the fillet in indi-vidual dishes with plenty of sauce. Cover the meat with slices of strong Provolone Valpadana P.D.O., sprinkle with parsley and serve.