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

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

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

In another bowl, whisk together the all-purpose flour, cake flour, baking powder, and salt.

Gradually add the dry ingredients to the wet ingredients, alternating with the limoncello, starting and ending with the flour mixture.

Fold in the lemon zest.

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

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

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

In a small bowl, mix the powdered sugar and limoncello until smooth.

Drizzle the glaze over the cooled pound cake.