How do you fancy your Butterbeer—chilled or frozen? Either way, you’ll never brew it at home the way it’s made at The Wizarding World of Harry Potter at Universal’s Islands of Adventure in Orlando, Fla. As a matter of fact, the recipe is a guarded secret.

The chefs at Universal Parks & Resorts invited Potter creator J.K. Rowling to sample the recipe they thought mirrored the drink she invented for her books. To their delight, she liked it! In its first year of sales, more than 2 million pints of Butterbeer were sold to happy Muggles and wannabe wizards, alike.

According to Chef Steve Jayson, vice-president and executive chef for Universal Parks & Resorts, “we spent years trying to come up with the perfect flavour and appearance of Butterbeer. We tried different combinations of a wide variety of ingredients until we felt we had the right one—which has a taste reminiscent of butterscotch and shortbread.”

Almost every patron of the Three Broomsticks restaurant orders at least one Butterbeer—two if they want to compare the frozen version to the chilled one. The bottom three-quarters of the non-alcoholic drink is a thick, dark brew poured from one tap then capped off with another creamy topping, guaranteeing a broad, foamy mustache over every grin that comes up for air.

Just like every other money-making recipe, the one for Butterbeer is kept under lock and key. Only a few trusted individuals know how to make it. As for who guards the recipe—well, it could be trolls, Fluffy the three-headed dog or maybe just a spell.