Preheat the oven to 350°F (175°C) and grease two 9-inch round cake pans.
In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt. Set this mixture aside.
In a large mixing bowl, beat the softened unsalted butter and granulated sugar together until light and fluffy.
Add the eggs one at a time, ensuring each is fully incorporated before adding the next.
Mix in the fresh lime juice and zest until well combined.
Gradually add the flour mixture to the wet ingredients, alternating with the buttermilk, beginning and ending with the flour mixture.
Divide the batter evenly between the prepared cake pans and smooth the tops.
Bake for 25-30 minutes, or until a toothpick inserted comes out clean. Allow to cool in the pans for 10 minutes before transferring to a wire rack.
Once cooled, frost with cream cheese frosting or lime glaze and garnish with additional lime zest.