Eight years after opening his restaurant on the Leith waterfront - which gained a Michelin star within six months of opening - the celebrity chef Tom Kitchin is poised to take a giant leap forward.

But first he must take a small step back. Today he closes the restaurant for two weeks, in order to allow the demolition of the original thick stone wall of the former 19th century whisky bond, which forms the back of the intimate dining space.

This major structural undertaking - the prospect of which Kitchin says makes him "go weak at the knees" - will be the final hurrah in the expansion of The Kitchin into the building next door, formerly the Chop Chop Chinese restaurant. The move, which has cost £1 million, will double The Kitchin's floor space, increase the number of covers by a third, expand the cramped kitchen, create a butchery and an exclusive private dining room.

Tom's Stockholm-born wife Michaela - a high-flyer who trained with the Savoy Group and previously executive-managed Claridge's, The Connaught and the Berkeley in London, and the seven-star Burj Al Arab hotel in Dubai - has been busy organising the transformation of the space next door with a stunning interior design concept aimed at retaining the nature-to-plate ethos of The Kitchin while upping the ante in terms of customer enjoyment.

Natural tones reflecting this country's landscape take centre stage, while fabrics and papers have been sourced from Scottish manufacturers such as Bute Fabrics and Timorous Beasties. She has been working closely with the Glasgow company Burns Interior Design - which also masterminded the look of the two other Kitchin restaurants Castle Terrace and Scran & Scallie - to create an understated on-trend look that is best described as Scandi-Scottish.

Stones and timbers, "dry stane" slate dykes, hand-blown bespoke glass lighting and specially-sourced Scottish sheepskins will be highlights with the restaurant re-opens on January 23. A bespoke Sonos sound system and newly commissioned crockery in gorgeous sludgy hues by Clare Dawdry of Castle Douglas complete the package though the Kitchin's trademark informal ambience, where tablecloths are anathema, will be retained.

Extra space - and staff - will help cut the waiting list of several months while allowing diners to stay at their table for longer. A new wine store will cater for the list of more than 2000 bottles of the 500 choices on the wine list - a far cry from the 30 they began with.

In the age of austerity, such a massive investment - of creative energy as well as cash - must surely be an indication of confidence, not only in the future of The Kitchin but also in the enduring appeal of Scotland's natural larder for its high-end domestic and international clientele.

Kitchin concurs: "This is a really exciting time where we're absolutely ready to go to another level. Over the eight years we've been here, Scotland has become so renowned for the quality of its hospitality around the world and is increasingly seen as a special place. Our international customers come to Edinburgh for the festivals, the rugby, golf, salmon fishing. We also have a loyal clientele from Glasgow, Aberdeen and the north-East of England.

"When we started out we worried that we'd used up all our savings, borrowed £50,000 and only had a few in for dinner. Now I cook for diners who fly up from London just for lunch." He also hosts top chefs every week like Pierre Koffman, Jason Atherton, Tom Aikens, Tom Kerridge, Andrew Fairlie and Martin Wishart, which he says is "the greatest compliment I could have".

Kitchin recently hosted a seven-course meal for David and Victoria Beckham and Gordon Ramsay, including hand-dived scallops baked in the shell served with a white wine and wild herb sauce, half Newhaven lobster cooked a la Plancha and finished with escargot butter, and saddle of Gilmerton house row deer served with seasonal autumn fruits.

But he acknowledges that success brings its own pressures. "When people are paying top buck you have to deliver something special. You have to keep reinventing and evolving. This business is very competitive and you have to remember that you're only as good as your last meal. The better you get at cooking, the greater the expectation becomes.

"The new space will allow us all to grow. For me and our team in the kitchen, it will mean more space and more importantly, the dining space will be more comfortable for our guests."

Kitchin, who has long been passionate about using traditional Scottish cuts in his French-style cooking, most notably pig's head and ears, sweetbreads, offal, tripe, bone marrow, locally sourced cod cheek, teal, woodcock, rabbit kidneys and a range of prime ingredients, is not planning to change his menu - at least, not until the new season comes along.

"Everything I do is 100% seasonal and that will not change," he says. Even his desserts eschew imported fruits like mango, pineapple and coconuts in favour of locally sourced sea buckthorn, plums, pumpkin, elderberries pears and a range of local cheeses. To this end his menus - a la carte, tasting, lunch, daily-changing seasonal - come with a map of Scotland which indicates where every ingredient is sourced.

It's clear Kitchin's commitment to Edinburgh is heartfelt. "With this expansion we're taking the biggest step it's possible for us to take. It's like the difference between choosing hand-dived scallops from Skye over dredged ones; we've gone for the best we can. This is our big chance. Even saying that makes my knees go weak," he says.

"To get to this stage, to be able to expand our business like this after eight years, is incredible. It's our customers who have allowed us to do it. This is our thank you for their support."

*The Kitchin re-opens on January 23, 2015. Tables are available for reservation now (Tel: 0131-555 1755; thekitchin.com).