Preheat the oven to 200°C (390°F).
Slice one apple into 2 cm rings and place them in the centre of a large roasting tray.
Place the pork on top of the apple slices. Rub the skin with olive oil and season generously with salt.
Roast for 20 minutes or until the crackling starts to form.
Meanwhile, cut the remaining apples, onions and squash into wedges.
Reduce the oven temperature to 170°C (330°F). Remove the tray, arrange the squash and onion around the pork, and sprinkle with mixed spice and ginger. Drizzle with olive oil and Calvados (or white wine).
Cover the tray loosely with foil and roast for 30 minutes.
Add the remaining apples, spoon over some of the pan juices, and roast uncovered for another 20 minutes.
If the pork is cooked through properly, transfer it to a plate, cover, and leave to rest.
Drizzle the vegetables and apples with a little maple syrup and return to the oven for 10 minutes, until lightly caramelised.
Transfer the vegetables to a serving dish. Use the pan juices to make a simple gravy (optional).
After resting the pork for 10 minutes, carve and serve with the roasted vegetables and your choice of sides. Pour over the gravy and enjoy!