BOIL beans in a large pot of water until tender-crisp, 4 to 5 min. Drain.
HEAT a large frying pan over medium- high. Add panko and hazelnuts. Stir frequently until lightly toasted, 2 to 3 min. Stir in butter until melted and just starting to brown, 3 min. Add beans and salt. Cook until beans are heated through, about 3 min.