Preheat the oven to 350°F (175°C). Grease and flour a 9x5-inch (23x13 cm) loaf pan.
In a large bowl, cream together the butter and sugar until light and fluffy, about 3 minutes. Beat in the eggs, one at a time, until fully incorporated. Stir in the vanilla extract.
In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk, and stirring until just combined. Fold in the lime zest and juice.
Pour the batter into the prepared pan and bake for 60 to 70 minutes, or until a toothpick inserted into the center comes out clean. Allow to cool in the pan for 10 minutes before turning out onto a wire rack to cool completely.
Make the glaze: In a small bowl, whisk together the confectioners’ sugar and lime juice until smooth. Drizzle over the cooled cake.
Interesting Facts
Key limes are smaller and more aromatic than regular limes.
Key lime juice is a popular ingredient in Key lime pie.