One cake will be a traditional fruit cake, decorated in an intricate floral theme with input from Middleton. It will be created by Fiona Cairns, a cakemaker to the stars - such as former Beatle Paul McCartney - who has built a thriving business since starting to bake at her kitchen table 25 years ago.
Middleton asked Cairns to use 16 different kinds of blooms and foliage, including roses, lily of the valley and ivy. A flower known as Sweet William is also on the list, said Cairns.
"It's cream and white. It's a traditional cake, but also I would say quite delicate, quite modern with a vintage element," described Cairns.
The second cake, requested by Prince William, will be a chocolate biscuit cake.
It will be made by McVitie's Cake Company, which has been making cakes for the royal family for decades.
The chocolate biscuit cake was William's favorite as a boy. Paul Courtney, the firm's cake designer, said the cake will have dark chocolate, broken up tea biscuits, and some secret ingredients.
The information about the cake clears up one of the questions about the royal couple's wedding day, but details about the rest of the menu and the wine and champagne that will be served still have not been released.
The cake is expected to be prominently displayed at the Buckingham Palace reception for about 600 guests that will follow the April 29 nuptials at Westminster Abbey.
Meantime, etiquette experts are advising guests of the royal couple to mind their manners. Experts gave some tips to help the wedding day go smoothly.
First, it's very important to be on time. Advisors say this particular wedding will have a lot of security, so guests should arrive extra early.
Women should wear dresses, but not anything skimpy and definitely not anything white. Men in the military should come in uniform. Civilians should wear business or morning suits, and top hats should not be worn inside the church.
Cellular phones should be turned off.
If you're attending the reception, remember never to begin a conversation with any member of the royal family. Experts say it's proper to let the royals start conversations. The Associated Press contributed to this report.