Pasta with chicken, feta & spicy tomato sauce

Cook pasta in boiling, salted water until al dente. Drain and toss in a little oil. Heat oil in a pan over medium heat and cook onion until it starts to soften. Add garlic and chilli, and cook for a further 1 minute. Add harissa and passata, and simmer for 5 minutes. Stir in chicken, feta, olives and parsley, then toss through pasta.