The Artisan Bakery - best known as the maker of 'London's best vegan croissant' has created a plant-based brioche.
The West London bakers were enlisted by the city's Patty & Bun burger chain to develop the roll.
The brioche will launch in all of Patty & Bun’s London restaurants, including its brand new Television Centre site, this week.
Brioche - a sweet type of bread - typically contains large amounts of butter and eggs.
The Artisan Bakery used a rapeseed oil blend in place of butter. Soya milk and nutritional yeast were used to naturally increase the sweetness, meaning less sugar is required for the new recipe.
Patty & Bun's Fred Webster-Trussell said: "The burger bun is the crowning glory of our burgers so to compromise with something less than delicious would be unthinkable. The Artisan Bakery stuck fast to our brief to create a buttery, but vegan version of a traditional brioche bun and we're delighted."
Andrew Murray from The Artisan Bakery added: "Patty & Bun have achieved their huge reputation and hit the top of every 'Best Burgers' list because their menu is inspiring.
"Their ingredients are fresh and high quality. We feel incredibly proud to now be a part of that story."
The chain launched its first ever vegan burger in its Patty & Bun’s Redchurch Street and Brighton outlets earlier this year - the Whoopi Goldburger, featuring a tempeh and mushroom fritter, topped with pickled cucumbers, diced onion, double smoked gouda (vegan) cheese, mustard, ketchup and lettuce.