Spread roast open; pound to 1/2-inch thickness with a meat mallet. Sprinkle evenly with 1 teaspoon salt and 1/2 teaspoon pepper.
Combine pork, parsley, egg, dry breadcrumbs, cognac, and remaining salt and pepper. Spread stuffing mixture on roast, leaving a 1/2-inch margin. Roll up roast jellyroll fashion. Wrap bacon in 4 strips around roast, and tie roll securely with string. Insert meat thermometer, if desired.
Place roast on a rack in a roasting pan. Dot with butter. Cover and bake at 300° for 1 hour. Uncover and bake 1 1/2 hours or until meat thermometer registers 170° (well done). Transfer roast to a serving platter. Strain pan drippings into a serving bowl. Place Dauphine Potatoes around roast; serve roast and potatoes with gravy.