Preheat your oven to 350 degrees Fahrenheit and generously grease and flour a bundt or small layer cake pan.

In a large bowl, cream the softened butter, granulated sugar, and the fresh citrus zest together for several minutes until light and fluffy.

Add the eggs one at a time, beating well after each addition to fully incorporate the citrus oils directly into the fats.

Alternate adding the all-purpose flour and the buttermilk into the creamed butter mixture, mixing until just combined.

Stir in the fresh citrus juice.

Pour the batter into the prepared pan and bake until a cake tester inserted into the center comes out clean, about 35 to 45 minutes.

While the baked cake is still warm, whisk together the powdered sugar and the Limoncello or Grand Marnier to create a smooth, thin glaze.

Use a toothpick or skewer to poke small holes all over the top of the warm cake.

Slowly pour the boozy glaze over the cake, allowing it to seep directly into the crumb for a sophisticated, damp texture.

Allow the cake to cool completely before inverting onto a platter to serve.