Place a large, non-stick frying pan over a high heat. Add the leeks, garlic, tomatoes, peas, chives and water, stir together, and cook for 6-8 minutes, until the water has been absorbed.
Stir the cooked pasta into the tomato mixture, then transfer to a shallow, ovenproof dish.
Preheat the oven to 220C/Gas 7. Mix all the topping ingredients in a bowl, season well, and pour over the pasta mixture. Place in the oven and cook for 15-20 minutes, or until lightly golden and bubbling. Allow to stand for 5 minutes before serving. Accompany with a crisp green salad.