Preheat oven to 325°.
Coat a large nonstick skillet with cooking spray; place over medium heat until hot. Add onion; sauté 2 minutes. Add mushrooms, 1/2 teaspoon thyme, and 1/8 teaspoon rosemary; sauté 3 minutes. Add apple and next 5 ingredients (apple through prunes); sauté 2 minutes or until apple is crisp-tender. Set aside.
Trim fat from pork roast. Cut a wide, deep pocket in side of roast. Stuff the apple mixture into pocket. Tie roast at 1-inch intervals with heavy string. Sprinkle roast with 1/2 teaspoon thyme, 1/4 teaspoon rosemary, and 1/8 teaspoon salt.
Place roast on a broiler pan coated with cooking spray. Insert meat thermometer into roast. Bake at 325° for 1 hour and 20 minutes or until meat thermometer registers 160°, basting frequently with apple juice. Garnish roast with rosemary sprigs, if desired.