Preheat the oven to 220C.
Score the skin of the pork, creating long lines or diamond shapes.
Mix the salt, pepper, ground cinnamon and ginger, then rub the pork skin with this.
Push the cloves between the inserts.
Put three or four pineapple slices in a baking tray and place the pork on top.
Cut the onion in half and put it in the tray together with the garlic.
Pour the pineapple juice in the tray.
Put the pork in the oven, skin-side facing upwards, and roast for 20-25 minutes or until the skin becomes golden brown and crispy.
Turn down the heat to 190C and roast for another 2 hours (35 minutes per 500g). Baste the skin with the tin juice a couple times to make the crackling nice & crunchy.
When the pork is cooked, remove it from the oven and rest for 30 minutes before carving.
While it’s resting, make the gravy from the cooking jus:
Remove the pineapple slices, onion and garlic, then carefully pour off the excess fat.
Add more tin juice or pineapple juice to the roasting tray, also a glass of stock or wine. Squeeze in the garlic flesh.
Bring to the boil on the hob, then add a spoonful of cornflour or crème fraîche and reduce it to a semi-thick gravy.
Carve the pork and serve with the pineapple slices, gravy and side dishes of your choice.