Preheat your oven to 350°F (175°C) and cream together softened unsalted butter and granulated sugar until light and fluffy, about 3-4 minutes. Add eggs one at a time, then key lime juice and zest.

In a separate bowl, sift together all-purpose flour and a pinch of salt. Gradually add the flour mixture to the butter and egg mixture while gently stirring until just combined.

Grease and flour a 9x5-inch loaf pan, pour the batter in, and bake for 50-60 minutes or until a toothpick comes out clean. Watch to avoid over-browning.

Let the cake cool in the pan for about 10 minutes, then invert onto a wire rack. Mix powdered sugar with fresh lime juice for glaze; drizzle over cool cake.