Grant Harrington has a single-minded obsession with butter.
In a small cabin in the middle of a field in Oxfordshire, he has dedicated his life to making the best butter he possibly can. But the quest started much further away, in the depth of the Swedish countryside.
"The first thing I ate in Sweden was butter," Harrington tells me. "And I remember being amazed at how much butterier it tasted than the butter I'd had at home."
At the time, he had just left a job working with Gordon Ramsay to spend a year cheffing at Faviken, and one of his first jobs was to make up the pats of butter.
"It intrigued me," Harrington remembers. "Why was the butter so good? How did they do it?"
You see, for most of us, there are two things you can spread on your bread to help the mastication process along: margarine or butter. That's it.
But Harrington had had an epiphany. He realised that some butters are more equal than others. One mouthful sent him in hot pursuit of the best, on a mission to make the most buttery butter he possibly could.
"I came back from Sweden and was doing all the food for my brother's wedding so I thought I might as well make the butter as well," he says. "Everyone raved about it. I also bust my anterior cruciate ligament at the wedding, so I couldn't go back to restaurant work. I spent a year doing horrible physio but it gave me time to research the perfect butter. I read a LOT of books."
First, there's the milk. Harrington uses Jersey cow milk because it has the highest fat content. Milk is also seasonal.
"What's in the field dramatically changes the flavour. In summer you'll get a floral milk, whereas in winter when the cows are eating silage, it's much more delicate," he explains. "So, when you culture butter, you're aiming to culture the bacteria that was most popular in the field where the cows were eating."
I'm already slightly lost. Science was never my strong suit at school and I'm quickly finding that butter-making is a bit more sophisticated than putting cream in a jar and giving it a good shake. Or the making of a good butter is, at any rate.
Harrington explains: "In the olden days, they used to leave milk to naturally separate over the course of a day. You know, when the cream floats to the top of a milk bottle? They'd do that in large containers, so the milk would naturally ferment and sour, and then they'd churn it. Now we've modernised the process, I have to add bacteria to the cream, like a cheese, to create a culture."
Harrington spent a year experimenting with different kinds of bacteria and how long to leave them to achieve the flavour that he wanted, before sending off his final product to be tested and approved in a lab. He found diacetyl, a bacteria that produces the butteriest flavour, promoting the production of butyric acid through the fermentation process.
He shows me a tray of fermented cream. It already looks buttery and smells like a kind of mild soft cheese. On the wall above the churn is a chart marking the pH content relative to fermentation time.
"You don't want to leave it too long otherwise it stops being buttery and begins to become cheesy," Harrington says. "After 19 hours, it's usually reached maximum acidity, but the flavour continues to develop. I go for a 160-hour ferment. Then I chill it right down before I churn it."
Harrington's churn is called Charlotte.
"She's French and a little temperamental, that's why I had to give her a name, because she wouldn't do everything I wanted her to," he adds.
By pouring the fermented cream into the churn, Harrington is able to "split" the fat from the liquid into globules of what's known as butter popcorn, but what looks more like scrambled egg. He drains off the buttermilk and then hand squeezes great lumps of it.
"Normally when butter makers get to this stage, they wash the butter with cold water, so you get clean flakes of butter," Harrington says. "I think I'm one of the only butter makers who doesn't. It makes no sense to me at all because buttermilk itself has such a great acidity to it. You need that, it's almost sweetness, to make it taste really good, and to add to the buttery-ness."
There's no detail in Harrington's process that hasn't been considered and weighed on its buttery merits. Including my personal body temperature.
"How cold are your hands?" he asks.
"Quite cold," I reply.
"Have a go then."
Squeezing and kneading the butter is not a job for the warm-blooded, else the butter melts in your hands. It's a satisfying feeling, like a giant buttery smelling stress ball. I'm pretty sure the buttermilk oozing out around my fingers isn't a bad moisturiser either.
"I should start courses," Harrington says. "If you've had a hard day, come and take your stress out on butter."
It's not a bad idea. Currently Harrington makes all the butter by himself, churning 120 litres a week in 20-litre batches. It's clearly a labour of love.
"When I first built this room, I hadn't thought about all the heat fridges give out," he says. "It got to early summer, my orders were massive, and it got warmer and warmer, and the butter just started melting. I ended up having to work night shifts from ten o'clock. Thankfully I got air conditioning."
Squeezed as hard as possible, the butter is then kneaded like bread to release even more liquid out, before Harrington salts it with pink Himalayan rock salt.
"This salt has a larger bacterial content than normal salt," he explains. "Most people think salt kills bacteria, but there's loads of salts that actually promote the process."
Harrington seems almost apologetic for the deep nerdiness of his expertise. But the proof of the butter is in the eating and every careful consideration has paid off. He supplies his butter to some of the best restaurants in the country, including Michelin-starred Nottingham restaurant Sat Bains and Tom Sellers' Restaurant Story.
The finished round is a healthy-looking, egg yolk-yellow colour, it smells incredible, and tastes±—well, let's try and not use the word butter. It's umami, slightly sweet, slightly salty, creamy but not cloying, and—oh sod it—I'd say he's achieved his aim. It's by far the butteriest butter I've ever eaten.
This article originally appeared on MUNCHIES in November 2015.