Butterfly the flank steak, cutting horizontally from a long side to within 1/2 in. of opposite side. Open and place on a large piece of heavy-duty aluminum foil (about 18 in. square). Sprinkle parsley, garlic and cheese over meat to within 1/2 in. of edges. Roll up tightly jell-roll style, starting with a long side. Wrap tightly in foil.
Place in a 13x9-in. baking dish. Bake at 325° for 1-1/2 hours or until meat reaches desired doneness (for medium-rare, a thermometer should read 135°; medium, 140°; medium-well, 145°). Let stand 10 minutes before slicing.