Guests at the royal wedding will be treated to not one, but two, cakes on 29 April.
One will be William's favourite chocolate biscuit cake, which is made from a special recipe involving Rich Tea biscuits and dark chocolate and is set in the freezer rather than baked in an oven.
Buckingham Palace has sent the recipe to chefs at McVitie's, who will make a giant version including 1,700 biscuits and nearly 40lb of chocolate.
The royal couple have also asked Leicestershire-based celebrity cake maker Fiona Cairns to create multitiered fruity masterpiece.
Kate has been totally hands-on in the planning for the cake. It is thought it will incorporate the couple's cipher, which will be released on the wedding day and is expected to be their entwined initials.
Kate has chosen pale colours for the cake and apparently wants a floral theme featuring the symbols of the four nations: an English rose, a Scottish thistle, a Welsh daffodil and an Irish shamrock.
When Fiona visited Clarence House six weeks ago to discuss the cake, Kate had designed 'mood boards' to show her what she wanted.
"She has guided us right from the beginning and has quite strong ideas," she said.
"She knew very much what she wanted and she brought us mood boards and told us what influences she would like us to use on the cake.
"The cake is multi-tiered, doesn't have colour – it's cream and white [icing] – and it's a traditional cake but also quite delicate and modern. All the tiers will have a different theme."
The Palace has said the cake will have 'a strong British floral theme' and will be decorated using intricate piping to create flowers, leaves and scrollwork, and accompanied with fresh fruit and flowers.
Asked how she felt to be designing the wedding cake, Mrs Cairns said: "I couldn't believe it. I'm very excited, very daunted and very privileged – a mixture of emotions."
Fiona is no stranger to high-profile cooking - she bakes a Christmas cake for Paul McCartney every year, and is a regular supplier to Harrods and Selfridges.
The 600 guests at the wedding breakfast will also be treated to William's childhood favourite, the McVitie's chocolate biscuit cake.
Paul Courtney, McVitie's cake design and development head chef, said he was excited about making Williams' favourite.
"It's an unbaked cake and it will be made in a test bakery where we develop new products as our factory lines are too big," he said.
"It has a couple of secret ingredients we can't tell you about but it will have dark chocolate, to give it a really nice flavour, and use Rich Tea biscuits that will be broken up.
"It will be decorated with chocolate display work which will be contemporary, modern and elegant.
"When Prince William was a young boy he would have it for tea and really enjoyed it."
Awww. Do you like the sound of the cakes?