Mix mayonnaise and chutney together in small bowl; set aside. Saute ham slices and pineapple in butter until lightly browned. Spread about 1 tablespoon chutney mixture on each cut side of onion rolls. For each sandwich, place ham slice over chutney mixture; top with 3 or 4 avocado slices and pineapple slice. Garnish with parsley and any remaining pineapple slices.