Toast the breadcrumbs: Heat a glug of oil in a small frying pan. Add half the chopped garlic and the breadcrumbs. Cook over medium heat for about 3 minutes until golden and crunchy. Season, toss together and drain on kitchen paper.
Cook the pasta: Boil the spaghetti in salted water until al dente, following packet instructions.
Fry the sardines: In a separate frying pan, heat a little oil and fry the remaining garlic and chilli for 1-2 minutes. Flake the sardines into chunks and toss in the pan.
Combine: Drain the pasta and add to the sardine pan. Toss well. Add the oregano leaves and season to taste.
Serve: Stir the rocket (arugula) through the pasta. Divide between plates and scatter the crispy garlic breadcrumbs over the top. Serve immediately.
