Requires Cooking (375). The recipe is gained by talking to the Washed-Up Mage behind the grate in The Underbelly of Dalaran. It is marked as a quest, so will appear over him.
This is a reference to a drink served in the Adventurer's Club at Walt Disney World's Pleasure Island. The much-loved club was closed in late 2008, and this appears to be the WoW developers' tribute to it.