These key lime pie cupcakes are as close to the real thing as you can get, in cupcake form anyway. There is even have a “pie crust” at the bottom of each cupcake made from graham cracker crumbs, butter, sugar and lime zest. The cake part of these key lime cupcakes consists of standard cake batter, with the exception of key lime juice, yogurt and key lime zest. The frosting even contains key limes (and a traditional buttercream mix), which makes them taste even more authentic!
Source Java Cupcake