1) Cook pasta according to package directions.
2) Combine clams, broth, onions and orange zest in a large frying pan over medium-high heat. Bring to a simmer and simmer for 5 minutes.
3) Toast bread crumbs in a small, dry pan over medium heat.
4) Drain pasta, adding 120ml of cooking water to clam mixture in frying pan. Simmer 1 minute.
5) Place pasta in a large serving bowl. Pour over clam mixture and top with toasted bread crumbs; serve immediately.