As befits a Benedictine monk, Brother Rainer knows an awful lot about the spirit, particularly the stuff in his cider brandy. 'It's at around 40 per cent,' he says, his accent still holding the gentle burr of his native Germany. 'It's very fragrant with all the appley notes you would find in the cider we use to make it. But it's definitely something you would want to sip.' Indeed. You don't want to go necking something that strong, and certainly not in the company of monks; the Benedictines don't much hold with binge drinking.

In any case the surroundings demand more decorous behaviour. We are at Ampleforth in North Yorkshire, home to the spired and vaulted public school, the abbey, its 83 monks and, most importantly, the orchard of 2,000 apple trees which are Brother Rainer's pride and joy. He leads me in, down rutted aisles of gnarled trees, the dark sloping earth that they grow on tangled with nettles and wild grasses. There is nothing manicured about this orchard and, on a bright, crisp autumn day, it is a deeply calming place to be.

'Ampleforth has been growing apples since the monks came here in 1802,' he says. 'But the first organised orchards were only planted by Abbot Smith in 1902.' Although some of the older monks remember cider being produced here before the Second World War, that didn't start in earnest until Brother Rainer was invited to take care of the orchard in 2001. The production of Ampleforth Cider Brandy is even more recent. The first batch was only ready in 2006, after three years in barrels, but in such small volumes they decided to keep quiet about it, for fear they wouldn't be able to fulfil demand. Only this year do they finally have enough - 6,000 bottles - to market it more widely.

Brother Rainer, all intense eyes, close-cropped hair and quizzical tufted eyebrows, slips a fruit-collecting box over his shoulders, muttering that monks don't generally go apple-picking in their habits. And don't even ask him to pose for photographs with any religious iconography. He's wary of attempts to parody a religious community like his. That said, he is fully alive to the marketing potential of their setting. 'Our cider brandy is not yet a money-spinning exercise,' he says, 'because the apples are so expensive, though it does eventually have to pay for itself.' So far it's available by mail order, or through selected retailers (including Lea & Sandeman's in London and Weeton's in Harrogate). 'But it also has an outreach element. It reminds people there are monasteries that are alive today. It presents our face to the outside world.'

It also continues an ancient tradition. Significant parts of our wine stores and liquor cabinets would be bare were it not for the efforts of religious communities. According to legend, Dom Pérignon - now produced by Moët & Chandon - is named after the monk claimed to have invented champagne and, as its name suggests, Châteauneuf-du-Pape wouldn't exist at all were it not for the involvement of religious orders. Then there is Chartreuse, a fair slab of the Belgian beer industry and, of course, Benedictine. 'All the really good drinks rely on expertise and recipes being handed down from one generation to another,' Brother Rainer says. 'In a monastery that's much easier to do.'

Which makes Brother Rainer sound like he's been in the order since he started shaving, but he hasn't. Born and raised in the German countryside near Dortmund around 50 years ago - Benedictines don't celebrate birthdays so his age has to be guessed at - he trained first as a chef, before studying medicine. He specialised in trauma, and then moved to this country to work in hospitals in the West Midlands. It was only 10 years ago, after finding himself increasingly restless and unfulfilled in his job, that he came to the abbey on a retreat and realised it was where he needed to be. As well as looking after the apples, he also tends to the seven elderly monks, some of whom are in their nineties, who are in the infirmary. It's comforting to know that, were I to drop to the ground with heart failure - a distinct possibility given the outrageous dish he later serves for lunch - Brother Rainer would be handy with a defibrillator.

We wander round the orchard, as Brother Rainer picks his fruit. 'The work is very repetitive,' he says. 'There's nothing that requires your mind to be acutely focused which is good, because certain of our prayers are also very repetitive and it lends itself to that.' They grow 43 varieties of apple, from the well known Bramley to the lesser known Kidd's Orange Red and the Ribston Pippin. The varieties, with their different seasons, means the abbey is supplied with apples throughout the year. The comely, nicely shaped fruit goes to the table; the rest to be juiced.

He leads me off to the presses in a ramshackle shed. At the back is a makeshift lab for chemical analysis - 'the medical training is useful' - and out in front is the 32-ton press. The air smells sweetly of recently juiced apples. 'Early on when I started looking after the orchards I had a choice. I could either make juice which would have needed pasteurisation or I could make cider.' It was, he says, an easy decision. The cider is fermented in huge plastic barrels. 'Not very romantic,' Brother Rainer admits. 'But they are much easier to clean than wooden ones.' Mostly he's self-taught, picking up tips from friends in Brittany. Not that he's always got it right. Cider is meant, by law, to be no more than 8.5 per cent alcohol. At times his has come out at 14 per cent. So what, I ask, is the Benedictine attitude to alcohol? 'We drink it.' Simple as that? 'Oh yes. It is written down that the brethren should have half a bottle a day - although it was probably far less alcoholic than today's output.'

Although he was always keen to turn his cider into something a bit stronger, Brother Rainer was stymied by the laws on distillation equipment. He simply wouldn't be producing enough. Instead, he drives his cider down to the highly regarded Somerset Cider Brandy Company in Martock, Somerset.

'It's an excellent product,' says Julian Temperley, who runs the firm and oversees its production. 'It's much younger than ours. They bottle after only a couple of years rather than the 10 or 15 that we sometimes run to. It might best be described as an apple eau de vie.' But what touches Temperley most is the care Brother Rainer takes over it. 'He sits here while we distil it and watches every last drop come out of the still. It never occurs to him just to leave the machine to do its job. He takes enormous pride in his orchard and his apples and it's lovely to see.'

It is lunchtime at Ampleforth and, after the small matter of mass - he is a monk, after all, and a certain amount of praying comes with the territory - Brother Rainer insists on preparing lunch for us. He cooks a dish called heaven and earth, a mixture of their own apples cooked down in their own apple juice, plus potatoes, topped with lardons of smoked bacon and sweet caramelised onions, the whole layered with lengths of crumbly, dense boudin noir sausage from France - a dish he says his mother used to cook .

The result is hardly pretty, the potatoes and fruit and crumbs of blood sausage piled all over each other, but it is exceptionally moreish; a blast of salt and sweet, of smoke and earth. And then of course there is the cider. It is yeasty and vibrant, bright and crisp. After the main course he pours us careful thimbles of the pale straw-coloured cider brandy. The flavour of the apples comes shining through, and the alcohol sends a warm but gentle burn all the way to our toes. I tell Brother Rainer how much I like it and he glows. After a day out at Ampleforth his spirit has most definitely moved me.

• Ampleforth Cider Brandy is available by mail order at ampleforth.org.uk