Whisky Glenfiddich 15 Year Old. Exemplifying our family’s tradition of innovation, our 15 Year Old expression is created using a technique pioneered by our Malt Master and its warm, spicy flavours are transformed with the alchemy of the Solera Vat. Aged in European oak sherry casks and new oak casks, the whisky is mellowed in our unique Solera Vat, a large oak tun inspired by the sherry bodegas of Spain and Portugal. Never emptied, and kept half full of whiskies since 1998, our Solera Vat is the culmination of curious minds and the pioneering spirit of our family. It’s also the secret behind this whisky becoming the first 15 year old expression to enter the top ten best selling single malts.