The royal couple will share the cake with their wedding guests on May 19 when they tie the knot at St George's Chapel, Windsor.
Chef Claire Ptak, originally from San Francisco and the owner of London based Violet Bakery in Hackney, only uses organic ingredients and is said to be Jamie Oliver's 'favourite cake maker.
She started out on a market stall but has now been chosen to bake the royal wedding cake.
Meghan previously interviewed Claire for her former lifestyle website TheTig.com, which may be why the royal couple have chosen the baker to make their wedding cake.
It had been suspected that Harry and Meghan would select a banana cake for their upcoming nuptials because the Prince loves 'anything with banana'.
But instead they have gone for a lemon and elderflower creation to reflect their springtime wedding date.
California-raised Claire, who has 62,000 followers on Instagram, formerly worked as a pastry chef under the legendary Alice Waters at Chez Panisse in Berkeley, California.
Upon moving to London, she worked at The Anchor and Hope as well as at St John and Moro.
Claire then started her own business as a market stall on Broadway Market, east London, cooking from home.
She then opened her bakery cafe in 2010.
However on TripAdvisor, recent visitors say staff at her bakery in east London are 'rude' and inefficient.
Last September, a customer complained of long wait times and lazy staff. Dr_S_Hall said: "The [staff] seem genuinely confused about the names of their products and try to give you the wrong one. They take a long time - longer than it is possible."
Claire's The Violet Bakery Cookbook has also had a string of negative reviews claiming that it contains incorrect measurements.
Emily B wrote on Amazon: "I agree with a lot of other reviewers ... I want so badly to love this book, but in nearly every recipe I have tried, a measurement is off, resulting in sub-par baked goods."
Claire makes wedding cakes on request and Harry and Meghan's lemon and elderflower creation appears to be a unique custom design just for the royal couple.
However her bakery Violet does offer customers a three-tiered Amalfi lemon layer cake feeding up to 60 people for £210 ($409), which may be the inspiration for the couple's chosen bake.
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The cake is made up of three layers of a 'fluffy vanilla sponge soaked with Amalfi lemon syrup', which is then filled with lemon curd, iced with lemon buttercream, and finished with sugared flower petals.
Who is Claire Ptak?
Claire Ptak is a food writer, food and prop stylist, recipe developer and consultant.
Hailing from San Francisco, she founded Violet Bakery in Hackney in 2010.
She started her business as a market stall on Broadway Market, originally cooking her bakes from home.
All of her cakes are baked with organic flour, sugar, milk and eggs.
She has written four cookbooks.
Claire also hosts a podcast on which she interviews successful women 'doing everyday things with amazing results' called Violet Sessions.
