This has got to be one of the most visually impressive desserts I have made. It looks so pretty in a glass and is so light and fluffy that no one will believe you made it! If you can't get Pimm's (a British drink) you could try substituting another hard liquor but I think it is worth the effort to find the Pimm's as it adds a very unique taste. If you are making this for a party, the zabaglione can be made as much as a day ahead of time. Preparation and cooking times include chilling.