Cook the penne in a large saucepan of salted boiling water according to packet instructions or until al dente. Drain and set aside.
Meanwhile, heat a little oil in a large non-stick frying pan over medium heat. Add the onion and cook for 5 minutes or until softened (do not allow to brown). Add the cream, bring to a simmer and cook for 2 minutes. Stir through the corn, peas, parmesan and chicken. Cook for another 2-3 minutes, then add the penne. Season with salt and pepper. Stir until well combined.
Preheat an oven grill on medium heat. Transfer the chicken mixture into a 4-cup capacity baking dish. Scatter with the cheese and place under preheated grill. Cook for 3-4 minutes or until golden on top. To serve, sprinkle with chopped flat-leaf parsley, if desired.