Royal wedding cake baker Claire Ptak is keeping her recipe for Prince Harry and Meghan Markle's big day under wraps for now.
Ms Ptak, who has been labelled London's hippest baker, is known for making indulgent organic bakes decorated with delicate flowers.
She has even been named as Jamie Oliver's favourite cake maker.
Oliver commissioned her to make a mocha gluten-free birthday cake for his wife Jools last year.
Harry and Ms Markle have opted for a lemon elderflower cake covered in buttercream.
Pastry chef Ms Ptak might take inspiration from a lemony recipe which belongs to her mother.
The owner of the trendy Violet Bakery in Hackney, east London, has written of Elisabeth Ptak's "legendary lemon bars".
The recipe features in Leon: Baking & Puddings, which Ms Ptak co-wrote.
She recommends using Californian Meyer or Amalfi lemons and describes the treat as "sharp and gooey with a sharp finish".
An article to which Ms Ptak contributed in The Guardian on the five best birthday cakes saw her recommend a red velvet one, which she was taught to make by her grandmother.
The piece also featured a lemon and elderflower drizzle cake by cook and food writer Rosie Reynolds, with ingredients including lemons, elderflower cordial, full-fat cream cheese and double cream.
It was decorated with edible flowers, sprigs of lemon thyme and lemon zest.
Ms Markle is known to be a fan of peonies, which will be in bloom at the time of her May 19 wedding, and Ms Ptak has used peonies on her stylish wedding cakes in the past.
Celebrity Masterchef winner Lisa Faulkner's recipe for elderflower, lemon and poppy seed layered cake uses Belvoir Elderflower Cordial and the finely grated zest of three lemons in the mix, as well as 10 eggs, unsalted butter, caster sugar, self-raising flour and poppy seeds.
Cordial is used again in the buttercream icing.
Unlike a rich fruit cake, which needs to be made well in advance and will keep ahead of the day, Harry and Ms Markle's lemon elderflower cake, with its fresh buttercream icing, will be crafted shortly before the May 19 wedding.
Harry's father the Prince of Wales and stepmother the Duchess of Cornwall were presented with a lemon and Cornish elderflower sponge cake last summer.
On a visit to Porthleven in Cornwall in July, Charles and Camilla cut into two lemon and elderflower cakes - one depicting the Prince's Highgrove House and the other a five-tier cake in the colour of the Duchess's 2005 wedding outfit.
They were made by Phil and Christine Jenson, who run luxury cake makers Peboryon.
The cakes were described by the firm as "layers of light and zesty lemon sponge" with "buttercream laced with wild Cornish elderflower curd".