While Highland Park 12 Year is in almost every malt maniac's cabinet and the 18 Year gets regular plaudits, the 15 Year has been a little forlorn within the lineup. Given pressure on their stocks, it looks like the distillery (or more likely the corporate folks at Edrington) has pulled the expression, probably to reserve more casks for the 18 Year and replaced it with Dark Origins at the same price point.
This is bottled at 43% probably with chill filtration and possibly without coloring (I've heard conflicting accounts of whether they use it or not now).
Highland Park 15 Year
Nose: maple syrup, integrated sherry, American oak (caramel, vanilla), baking spices, twiggy malt, heather, herbal, light peat, peach, strawberry, raspberry. After adding a few drops of water, the sherry and oak integrate, the baking spices resolve into woody cinnamon, and the peat fades away.
Taste: opens with sweet sherry, raisins, American oak with herbal/floral/heather-y peat overtones, mesquite honey, and darker sherry through the middle, fresh dry malt near the back as the sherry slips away to reveal a bit more peat and oak. After dilution the sweetness becomes stronger and brighter, with the oak and peat fading into the background.
Finish: sherry sweetness, gentle peat, malt, vanilla, a touch of oak and wine acidity
The defining feature of this Highland Park is the American oak. While, like its 12 and 18 year old counterparts, it is matured entirely in ex-sherry casks, the 15 Year is constructed with more American oak than European oak casks. This gives it character that you would expect from an ex-bourbon cask malt, but with plenty of sherry on top. The extra age has also softened the peat in comparison to its younger sibling, which gives it a much more approachable character. Instead of the whipsaw from sweetness to peat, the transition is more gentle. That's not to say that it's flat or insipid, though I do think that it, like the 12 Year, would have benefited from a bump to 46% and craft presentation. This goes double in Europe where it was bottled at 40% rather than 43% as it is in the States. Basically, if you enjoy sherry-driven malts and can find Highland Park 15 Year for under $80, which, after a cursory search appears to be possible in many places, it's a no-brainer. While the 18 Year gets most of the plaudits, in an era of rising prices the 15 Year can be a solid value.