Whiz the onions, spices and meat in a food processor until chopped together. Pulse in the eggs and the breadcrumbs and season generously with sea salt and black pepper. Tip on to a work surface and shape into 8 balls.
Strip the leaves from the bottom of the sprigs of rosemary, leaving the leaves on the tops and reserving the stripped leaves. Cut the ends of the rosemary sprigs at an angle and push one through each ball of meat, leaving the tufty, leafy bit sticking out.
Cut the tomatoes in half and squeeze out and discard most of the seeds. Chop up a bit more and spread out in 1 or 2 roasting trays. Peel and chop the garlic and add to the trays. Roughly chop the reserved rosemary leaves and add to the trays. Season and drizzle with just a little olive oil.
Place a baking rack over each tray and lay the meatloaf balls on top. Put the tray in the oven for 30 minutes or until the meat is cooked and crisp on the outside. Cover the rosemary sticks with foil if they start to look too brown.
Serve 1 meatloaf per person with some tomatoes and juices from the tray. (The tomatoes taste fantastic with all the meaty juices from the meatloaf stirred in.) Sprinkle with fresh basil just before serving.