Kate Middleton and Prince William, now officially the Duchess and Duke of Cambridge, greeted foreign dignitaries this afternoon at Buckingham Palace during their brunch reception! It was their second engagement following this morning's royal wedding , and the newlyweds left the palace in an Aston Martin driven by William himself. The car even featured a license plate that read "JU5T WED"! Kate was still wearing her custom-made McQueen wedding gown , though she's apparently already changed into her second Sarah Burton-designed dress. As she and William said hello to guests today, a team of more than a half-dozen bakers were busy putting the finishing touches on the breathtaking cake. The towering confection features eight tiers and hundreds of sugar flowers. Prince Charles will host this evening's party for the couple, and festivities are expected to continue on well into the night. The Middletons, meanwhile, are throwing a small gathering at The Goring Hotel for friends and family not invited to the 350-person palace dinner. Carole and Michael, Kate's parents, will join the royals for the meal once wrapping up their private celebrations at the accommodations where Kate spent her last night as a single woman.