To make olive crumbs, heat oven to 140°C. Drain and lay out olives evenly on a baking tray and cook for 1½-2 hours until dried.
Transfer olives to a chopping board, then chop finely into crumbs. If olives are still a bit wet inside, put them back in oven for 10 minutes or so until dry. Grind dried olives coarsely using a food processor.