Nàdurra First Fill Oloroso has been matured exclusively in First Fill Oloroso Sherry Oak casks from the Jerez region in Spain; The most highly prized and sought-after casks used by whisky makers. First Fill Oloroso Sherry casks have long been famed for imparting wonderfully rich, luxurious flavours of dried fruits and warm spices to single malt whisky.