After an almost decade-long absence from shelves, the limited-edition Glenmorangie Astar is reborn.

While it is made the same way as the original version, Glenmorangie's head of maturing whisky stocks Brendon McCarron tells The Sunday Times that the new Astar is a "reimagining of the original".

The cult favourite, limited-edition single malt scotch is matured in tailor-made oak casks from trees grown in the Ozark mountains of Missouri.

In fact, the original version of Astar, first released in 2008, had to be withdrawn in 2012 because the availability of bespoke casks proved difficult to sustain.

"We literally choose the trees that are going to be made into casks and, from that stage, we are involved in every step of the process," he says.

Every variable is controlled by Glenmorangie's exacting specifications, including the use of tight-grained, slow-growth trees.

"You get more porosity, so the whisky is going to soak more easily into the wood," says Mr McCarron, who is in his late 30s.

The wood for the casks is then air-dried instead of dried in a kiln for at least two years, before the casks are slightly toasted and heavily charred. They are then filled with bourbon and seasoned for exactly four years before they are emptied, shipped to Scotland and filled with Glenmorangie spirit.

"You could say it's a first-fill exbourbon cask whisky, but it's bespoke - a tailored suit versus buying one off the peg," he says.

Due to popular demand from customers, it made its return to shelves worldwide, and Singapore, late last year.

"First, the original Astar was really loved and, second, more and more people are asking for cask strength whisky," he says of the decision to bring it back.

Cask strength whisky is undiluted and bottled at the proof at which it is drawn from the barrel. But the 2017 version of Astar, which is Gaellic for "journey", is not the exact same liquid as its predecessor.

While the original Astar came in at 57.1 per cent alcohol by volume (ABV), the 2017 version is bottled at the more palatable 52.5 per cent ABV.

"I love the original Astar, but it was too high in strength, even for me, and it was better with a little bit of water," he says.

It is also slightly different on the nose and palate. He describes the new version as "brighter in terms of citrus and fresh squeezed lemon, but the original Astar was more toasty and honeyed with clove spice".

Adding water also brings out the hallmark Glenmorangie flavours of stone fruit such as apricot, peaches and nectarines. But he insists they are "fine margins of difference" between the original and the update.

Mr McCarron, who joined the company in 2014, has a long history with whisky, having worked in every step of whisky making, from malting barley to disgorging - or releasing mature whisky from barrels.

"The only bit I hadn't done was maturation and understanding the wood, which is what I do now," he says.

Historically, Glenmorangie is synonymous with its cask management practices. In particular, Glenmorangie's director of distilling and whisky creation, Dr Bill Lumsden, is known for his pioneering wood management techniques and experimentation with casks at various ages.

Under Dr Lumsden's watch, Mr McCarron has been involved with the production of Milsean, the seventh release in Glenmorangie's Private Edition series, and the travel retail exclusive, Glenmorangie 19 Year Old, among other expressions.

But given that most of his experience was with making the raw spirit, he says "he wants to experiment with flavours and textures".

Like his boss Dr Lumsden, Mr Mc- Carron has an experimental streak.

"There were certain things I wanted to do (at previous companies I worked at) and I was just told no, so you make the same spirit every day, every week of the year - which is what most distilleries do," he says.

"But I knew Dr Lumsden specialises in using different casks and that Glenmorangie was doing things, so that attracted me."

He has already laid down some experimental casks. But with the time it takes whisky to age, it is about the long game.

"It's going to take 10 years before I realise if it is good or not... but I hope they are going to be brilliant."

• Glenmorangie Astar is available at liquor stores and whisky specialists, such as Le Vigne and The Whisky Distillery, with a recommend retail price of $240.