Prepare the chicken by chopping into bite-sized chunks. Set aside.
Heat half the olive oil in a large frying pan over a medium heat. Add the onion and garlic and fry for 1 minute. Add the chicken and courgette and fry for about 8 minutes, until the chicken is cooked through with no pink remaining.
Meanwhile, bring a large pan of water to the boil, add the pasta and cook for 8 minutes.
Drain the pasta and stir into the chicken mixture with the remaining olive oil, the chopped parsley, lemon zest and juice. Combine well and serve.