Preheat oven to 350°F (175°C). Grease and flour a 9-inch springform pan.

In a large bowl, whisk together flour, sugar, baking powder, baking soda, and salt.

In a separate bowl, cream together butter and sugar until light and fluffy. Beat in eggs one at a time, then stir in the limoncello.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Pour batter into the prepared pan and bake for 30-35 minutes, or until a wooden skewer inserted into the center comes out clean.

Let the cake cool in the pan for 10 minutes before inverting it onto a wire rack to cool completely.

While the cake is cooling, prepare the frosting: In a bowl, beat together mascarpone cheese, powdered sugar, limoncello, and lemon zest until smooth and creamy.

Once the cake is completely cool, frost it with the mascarpone frosting and garnish with lemon zest (optional)