Whisk together the flour, baking powder, salt, and lemon zest. Set aside.

Using an electric mixer on medium speed, beat the butter and sugar until light and fluffy. Add the eggs, one at a time, mixing well after each addition. Mix in the lemon juice.

Reduce mixer speed to low. Add the flour mixture in three portions, alternating with two portions of milk. Mix just until combined.

Divide the batter evenly between the prepared pans. Spread evenly.

Bake 30 to 35 minutes, or until a pick inserted into the center of the cakes comes out clean. Cool the cakes in the pans for 10 minutes. Then invert the cakes onto a wire rack to cool completely.

Using an electric mixer on medium speed, beat the mascarpone, cream, and lemon curd until thoroughly combined and smooth. Do not over-mix.

Place one cooled cake layer on a cake plate. Brush or drizzle about half of the Limoncello onto the cake. Spread about half of the frosting over the top of the cake.

Place the other cake layer on top of the frosted layer. Brush with the remaining Limoncello. Spread the remaining frosting over the top of the cake.

Chill the cake for at least an hour before serving to allow the frosting to set.