Gently boil the macaroni in salted water. Add the cauliflower to the same pan after about 5 minutes and leave to simmer for 15 minutes til both are cooked. Drain and set aside.
Turn the heat down low and pour in the apple and yogurt. Mix in the cheese til melted.
Return the macaroni and cauliflower to the pan, mix well and sprinkle over the parsley to serve.