Prince Harry and Meghan Markle have chosen an organic lemon and elderflower cake for their wedding in May.
Instead of a more traditional fruit cake, it will involve "spring" flavours and be covered with buttercream and decorated with fresh flowers.
The couple have enlisted Californian pastry chef and food writer Claire Ptak, owner of the Violet Bakery in east London, to make it.
Ms Ptak said she was delighted and that she shared the couple's values on food.
Kensington Palace said the couple were "very much looking forward to sharing" the cake with their wedding guests on 19 May.
Like Ms Markle, Ms Ptak was raised in California. She worked as a pastry chef at Chez Panisse under chef and campaigner Alice Waters.
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She later moved to the UK where she worked at The Anchor and Hope gastropub in Waterloo and set up a market stall on Broadway Market, east London.
She said: "Knowing that they really share the same values as I do about food provenance, sustainability, seasonality and most importantly flavour, makes this the most exciting event to be a part of."
Ms Markle has previously interviewed Ms Ptak for her former lifestyle website TheTig.com which covered topics such as food, beauty, fashion and travel.
Wedding cakes of the past
Prior to the wedding of Queen Victoria in 1840, wedding cakes were not considered an important part of the celebrations. Instead guests at the wedding banquet were often offered a slice of "bride pie".
Queen Victoria and Prince Albert's own cake weighed 300lb and featured the figure of Britannia blessing the bride and groom - who were dressed in ancient Greek costume.
In 2016 a man brought a leftover slice of the wedding cake for £1,500 at an auction.
In more recent royal history, the Duke and Duchess of Cambridge had two cakes for their wedding day.
The first was an eight-tiered iced fruit cake decorated with 900 delicate sugar paste flowers. The second was an unbaked chocolate biscuit cake - a favourite from Prince William's childhood - made from broken up rich tea biscuits by the company McVitie's.
McVitie and Price also made the Queen and Duke of Edinburgh's wedding cake in 1947 - it measured 9ft high.
Instead of flowers, this cake was decorated with painted panels of the armorial bearings of both families, monograms of the couple and sugar-iced figures depicting their favourite activities.
The cake was made using ingredients given as a wedding gift by the Australian Girl Guides as rationing was still in place.
Prince Charles and Princess Diana's wedding cake was 5ft high, weighed 255lb, and was made by the Royal Navy's Cookery school.