In a large pan heat the oil and sauté the onion for 5 minutes until softened. Tip onto a plate and set aside.
Meanwhile, cook the pasta according to the packet instructions in plenty of lightly salted water. Four minutes before the pasta should be cooked increase the heat and add the prepared vegetable to the water and simmer.
Preheat the oven to 180˚C, 160˚C fan, gas mark 4.
To make the sauce pour the milk into the same pan the onions were sautéed in and add the butter and flour. Heat over a medium heat stirring continuously. Within a few minutes as the milk reaches simmering point you will have a smooth but thin sauce. Remove from the heat and add the grated Applewood. The cheese will soon melt and can be easily stirred in to create a smooth sauce. Season to taste.
When the pasta is cooked, drain and tip into the cheese sauce along with the chicken and vegetables, and parsley. Mix well and pour everything into an ovenproof dish.
Sprinkle over the grated Applewood and place in the preheated oven for 20 minutes until the vegetables are tender and the topping is golden brown.