Preheat oven to 325 degrees
Cream together butter and sugar
Then add eggs one at a time, beating in between additions.
Add the lime zest and juice, vanilla, and buttermilk, then mix well.
Then add flour, baking powder, salt, and mix well.
Fill cupcake liners 3/4 full
Bake. at 325º.
For regular cupcakes, bake 20-25 minutes. Miniature cupcakes 10-12 mins.