Grease and flour your cupcake or mini-cupcake pans.
In the bowl of an electric mixer fitted with a paddle attachment whip the butter and 2 cups/480 ml of granulated sugar at medium speed until light and fluffy about 3-5 minutes.
Add the eggs one at a time and the key lime zest.
In a medium-sized bowl sift together the flour baking powder baking soda and salt.
In a separate bowl combine ¼ cup/60 ml of key lime juice the buttermilk and the vanilla.
Add the flour and buttermilk mixtures alternately to the batter beginning and ending with the flour mixture.
Transfer the batter into your cupcake pans and bake for 25-30 minutes or until a test toothpick comes out clean from the middle of the cake. Remove your Key Lime in da Coconut Cupcakes from the oven let them cool completely and enjoy!