Clean the pork tenderloin from the silver skin and fat. Save the scarps, add to a pot of water, and simmer to make the stock for the sauce. Once the stock has reduced to about 6 oz, strain and place in a clean saucepot

Then slice the pork on the side almost all the way through. Fold open and lay on a cutting board, and pound the pork out with a mallet

In a saucepan, add the butter and mushrooms and sauté until soft. Add the apricots and cook for 3 minutes. Then add the fresh thyme and deglaze with red wine. Season with salt and pepper and cool down. While the filling is cooling, lay out the pork, season with salt and pepper and brush the Dijon mustard. Then place the prosciutto on the meat and add the filling. Roll tight and tie with butcher's twine. Place in fridge until sauce is ready

In a saucepan, add the oil and sear the pork off on all sides; remove the pork and place in a 400°F oven for 6 minutes for a medium rare; remove from oven and let rest for 10 minutes before slicing. Deglaze the pan with water and add the juice and dippings to the sauce that has been cooking

Place the stock on the stove and bring it to a boil; add the Dijon mustard and simmer for 5 minutes, then add the heavy cream and fresh rosemary and reduce by half. Add the drippings and simmer for 5 minutes, then add the Calvados and simmer for 3 minutes. Turn the heat down, season with salt and pepper and add 1 tablespoon of sweet butter to the sauce and keep warm

Slice the pork and drizzle the sauce over the meat