Violet Bakery’s lemon-elderflower-meringue-buttercream creation is taking shape for the big day tomorrow (19 May).

Chef Claire Ptak is finishing up the layered lemon and elderflower cake, which will be displayed as part of a special installation.

The cake will be unveiled at St George’s Hall after the Windsor Castle wedding ceremony for Prince Harry and Meghan Markle.

"It’s a kind of an ethereal, floral flavour, which I think is very special, especially for a wedding,” commented Ptak in a video released by the royal family.

The cake contains 200 Amalfi lemons from the Italian coast, 500 organic eggs from Suffolk, 20kg butter, 20kg flour, 20kg sugar and 10 bottles of elderflower cordial made of buds from the Queen’s Sandringham estate in Norfolk. The elderflower syrup uses a recipe created for the couple.

The sponge is sandwiched between layers of lemon curd and buttercream, while the outside is decorated with a white elderflower Swiss meringue buttercream. It will be topped with spring flowers including peonies, and white and cream roses.

Ptak added: “The buttercream is sweet and the lemon curd is very tart so you get a very lovely thing happening when you take a bite, which is to get all of these flavours and sensations perfectly balanced.”

The decorative flowers will be removed before the cake is served, but the slices will be plated up with edible rose petals.

Ptak, who owns the Violet Bakery in Hackney, has been working with her team of six bakers full-time for five days in the kitchens of Buckingham Palace. The baker also said she had to call in backup from former colleagues to ensure she had enough staff to work on the cake, as well as keep her bakery open in Hackney.

Six hundred guests will be served slices of cake at the lunch-time reception following the wedding ceremony.

Any left-over cake will be donated to charity.