In a medium bowl, cream together the butter and sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla.
In a separate bowl, sift together the flour, baking powder, and salt. Gradually stir the dry ingredients into the wet mixture. Mix in the key lime juice until combined.
Roll dough into 1 inch balls and roll in the powdered sugar. Place cookies 2 inches apart on an ungreased cookie sheet.
Bake for 10 to 12 minutes in the preheated oven. Allow cookies to cool on baking sheet for 5 minutes before removing to a wire rack to cool completely.
Interesting Facts
Key limes are smaller, more acidic, and more aromatic than regular limes.
Key limes have a more intense flavor than regular limes.
Key limes are named after the Florida Keys where they are most commonly grown.
Key lime juice is often used to make key lime pie and other desserts.