In a large bowl, combine the mayonnaise, parsley, mustard and onion. Stir in the chicken, bacon and 3/4 cup cheese., Unroll crescent dough; separate into 16 triangles. Arrange on an ungreased 12-in. round pizza pan, forming a ring with pointed ends facing outer edge of pan and wide ends overlapping. , Spoon chicken mixture over wide ends; fold points over filling and tuck under wide ends (filling will be visible). Chop half of a tomato; set aside. Slice remaining tomatoes; place over filling and tuck into dough., Bake at 375° for 20-25 minutes or until golden brown. Sprinkle with remaining cheese. Let stand for 5 minutes. Place lettuce in center of ring; sprinkle with chopped tomato.