Preheat the oven to 350°F (175°C). Grease and flour a loaf pan.

In a mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.

Add the eggs one at a time, mixing well after each addition.

In a separate bowl, whisk together the flour, baking powder, and salt.

Gradually add the dry ingredients to the butter mixture, alternating with the key lime juice. Mix until just combined.

Fold in the key lime zest.

Pour the batter into the prepared loaf pan and smooth the top.

Bake for 60 minutes or until a toothpick inserted into the center comes out clean.

Let the cake cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.

In a small bowl, whisk together the powdered sugar and key lime juice until smooth.

Drizzle the glaze over the cooled cake.