Melt half the butter with the oil in a large, flameproof casserole with a tight-fitting lid large enough to hold the rabbit in a single layer. Lightly season the rabbit with salt and add to the pan with the onions, celery, crushed chillies and rosemary. Cover and cook over a low heat for 1½ hours, turning the rabbit pieces every 30 minutes.
Uncover the pan, increase the heat to high and boil until most of the juices released by the rabbit during cooking have evaporated. Add the lemon and olives, stir well, then pour in the wine. Bring to the boil and boil for 2 minutes, for the alcohol to evaporate.
Pour in the stock and simmer, turning and basting the rabbit occasionally, for a further 10–12 minutes until you have a rich, syrupy sauce. Serve hot.