Preheat the oven to 350°F (175°C). Grease and flour a 9-inch round cake 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, combine the all-purpose flour, cake flour, and baking powder.

Gradually add the flour mixture to the butter mixture, alternating with buttermilk, starting and ending with the flour mixture.

Stir in the lemon zest, vanilla extract, and lemon juice until well combined.

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

Bake for 30 minutes or until a toothpick inserted into the center comes out clean.

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

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

Once the cake is completely cooled, drizzle the lemon glaze over the top.