Bring a large saucepan of water to the boil, then add the spaghetti and cook for 12-13 minutes or according to the packet instructions until al dente. Trim the green beans and add to the pan for the last 2 minutes of the cooking time. Drain, then return to the pan.
Meanwhile, in a mini food processor or with a pestle and mortar, whizz/grind 100g of the olives with the anchovies and garlic. Drizzle in the olive oil and add half the parsley, then whizz/stir until you have a smooth sauce.
Stir the sauce through the pasta and green beans, along with the remaining olives and parsley leaves. Season generously with salt and pepper, then divide among 4 plates and serve straightaway