Set up your barbecue for direct cooking. Place a casserole dish (without lid) in the centre and add the oil. Preheat on high for ten minutes.
For the meatballs, combine all the ingredients together in a bowl. Roll into small 3cm balls (makes approx. 25-30 balls).
Once the barbecue is preheated, leave the heat setting on high. Add the garlic, onion, chilli, salt and pepper to the casserole dish and fry for 2-3 minutes. At the same time, add the meatballs to the grill and cook for 2-3 minutes per side. Once you have turned the meatballs, remove the casserole dish from the barbecue using heatproof/oven gloves.
Add the passata sauce and beef stock to the casserole and stir in. When the meatballs are cooked, remove them from the grill and add to the casserole.
Turn your barbecue to the roast setting (add a convection tray and trivet if using a Q). Place the lid on the casserole dish and place on the trivet. Cook for 45 minutes.
Remove the casserole lid and continue cooking, stirring occasionally, for another 15 minutes. Just before serving, stir in the chopped basil and sprinkle with the grated parmesan.