Preheat the oven to 350 F (177 C). Grease and line the bottom of a 9-inch (23 cm) springform or cake pan with parchment paper.

In a large bowl, whisk together the flour, baking powder and salt together until well combined.

In a large mixing bowl fitted with whisk attachment, whisk the sugar and lemon zest together until they are the consistency of wet sand.

On low, whisk the eggs and lemon sugar together until all the eggs are combined. Increase the speed to high and whip for 2 - 3 minutes until thick and light yellow in color.

With the mixture on low speed, stream in the olive oil, followed by the limoncello, lemon juice and sour cream.

Once all the ingredients are mixed in, mix together for another minute on low to fully combine. Scrape the sides and bottom of the mixing bowl as needed. On low, whisk in the dry ingredients until just incorporated.

Evenly pour the limoncello and lemon cake batter into the prepared pan. Bake for 35 - 45 minutes or until a toothpick inserted into the center comes out clean or with a few moist crumbs.

Cool the cake in the pan for 15 minutes. Gently release the side of the springform pan, remove the ring and allow the cake to cool completely before topping with frosting.

Place a mixing bowl and whisk attachment in the fridge or freezer for about 15 - 20 minutes before making the frosting.

On low, whisk the mascarpone cheese until smooth. Mix in the vanilla extract and powdered sugar until well combined.

Slowly mix in the heavy cream on low speed. Increase the mixer speed to medium for about 2 - 3 minutes or until the frosting is light and fluffy.

Once the cake is completely cooled, top the cake with the mascarpone frosting. Create decorative swirls using the back of a spoon and drop dollops of lemon curd into the swirls.

Using the back of a spoon, gently swirl the curd into the swirls of mascarpone frosting.