Cook pasta in a saucepan of boiling salted water for 10–12 minutes or until al dente. Drain, return to the pan and keep warm.
Heat the butter and oil in a large frying pan over medium heat. Add the breadcrumbs, garlic and anchovies and cook for 2–3 minutes or until golden. Add to the pasta with the rocket and caramelised onion and toss to combine. Serves 4.