Icelandic bakery uses volcanic energy to make 'thunderbread'

Siggi Rafn Hilmarsson buries his dough underground where it is baked by volcanic hot springs. Photo / Laugarvatn Fontana

Through the last couple years, during various states of lockdown, many people across New Zealand become slightly obsessed with baking bread. As months went on, maybe you experimented a little, adding new ingredients or testing new recipes.

But few of us probably went as far as to bake our bread using geothermal springs.

Yet, at Laugarvatn Fontana in Iceland, that's exactly what they do.

A group dig amongst the sand and water to find the tins of hverabrauð. Photo / Fontana Iceland, Instagram

Wander along the shores of Lake Laugarvatn and you may spot people standing around large mound earth with a shovel in hand. After a little digging through the black sand and boiling water, they'll unearth a sealed stainless-steel pot. Inside, beneath the layers of plastic wrap, will be a golden-brown loaf of rye bread, baked to perfection.

This is the way it's done at Laugarvatn Fontana, a bakery that use the heat of local geothermal springs to bake their hverabrauð, a subtly sweet, dense bread often eaten with butter, trout and hard-boiled eggs.

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Hverabrauð literally translates to "hot spring bread", and its exciting nickname "þrumari" means "thunder bread". A fact that becomes less exciting when you realise it refers to the gassiness it can cause if you eat too much.

As the name suggests, the bread was traditionally baked using hot springs, however, most Icelandic bakeries now use modern ovens.

Located between the Eurasian and North America tectonic plates called the Mid-Atlantic Ridge, Laugarvatn Fontana is perfectly positioned for following old-school baking methods, which they've followed for more than a century.

Laugarvatn local and Laugarvatn Fontana general manager Sigurður "Siggi" Rafn Hilmarsson said, at first, he didn't consider hverabrauð to be anything special.

Hilmarsson learned the art of hverabrauð from his grandmother and had used her recipe for decades as part of a breakfast he served to guests at a hotel he ran with his wife.

One day, on a whim, he decided to invite guests to join him for his morning walks to collect the loaves. Then, he realised just how unique and exciting this simple bread was.

"In the evening, when I was going to pick up the bread, I went to the hot springs but suddenly remembered that I had put this note up in the lobby," he told Atlas Obscura.

"When I went back to the hotel, there were 80 people waiting for me."

Hilmarsson was then inspired to open up the bakery and spa in 2011 and offer rye bread tours for curious visitors.

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After keeping his grandmother's recipe a secret for decades, Hilmarsson finally decided to share it so people could make it at home (likely without the volcanic hot springs).

Those who are lucky enough to try a piece may be surprised that no cinnamon or other spices are used, just rye flour, all-purpose flour, baking powder, salt, sugar and cow's milk.

Hilmarsson said it's the slow, extremely hot cooking process that gives the bread its unique taste.

"It creates a unique taste and texture with much more flavour," he said.

The spring water can reach a temperature of 95 degrees Celsius, creating a natural earth oven.