Rinse the livers and pat them dry on kitchen paper. Cut each into about 4 pieces, cutting out and discarding any white parts. Season with salt and pepper.
Heat the butter and oil in a frying pan. When it is very hot, add the livers and fry them quickly, turning them so they brown evenly, for 5 minutes or until golden. If you prefer the livers well done, fry them for a further couple of minutes. Add the raisins and fry for 1 minute. Remove the livers and raisins with a slotted spoon and keep warm.
Add the Marsala to the pan and bring to the boil. Cook for a couple of minutes until syrupy, then stir in the lemon juice. Pour the sauce over the livers and serve scattered with chives.