Royal couple choose lemon elderflower cake for wedding

"Prince Harry and Ms. Markle have asked Ms. Ptak to create a lemon elderflower cake to incorporate the bright flavours of spring," Kensington Palace, the prince's official residence in London, said in a statement.

"It will be covered with buttercream and decorated with fresh flowers."

The pair were "very much looking forward to sharing this cake with their wedding guests," it added.

California-raised Ptak is a food writer and stylist, recipe developer and consultant, as well as the owner of the small but celebrated Violet bakery in east London.

She started the business as a stall on trendy Broadway Market, before opening her cafe nearby in 2010 with a focus on using high quality, seasonal and organic ingredients.

Ptak had previously worked as a pastry chef under renowned chef Alice Waters at her Chez Panisse restaurant in Berkeley, California.

"I can't tell you how delighted I am to be chosen to make Prince Harry and Ms. Markle’s wedding cake," she said in the statement.

"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."

Fellow American Markle, a former actress, used to run her own lifestyle website, and previously interviewed Ptak for her blog.

She and Prince Harry will marry at St George's Chapel, Windsor Castle, a residence of Queen Elizabeth II's located west of London, on May 19.