Preheat your oven to 350°F (175°C) and grease two 8-inch round cake pans with butter or non-stick spray, lining the bottoms with parchment paper. In a bowl, whisk together the all-purpose flour, baking powder, and a pinch of salt. In a separate large bowl, beat the eggs and granulated sugar until thick and pale, about 5–7 minutes. Fold in the vanilla extract and lemon zest, then gently incorporate the dry ingredients until just combined. Divide the batter between the pans, smooth the tops, and bake for 18–20 minutes, or until the tops are golden and spring back when touched.

Allow the cakes to cool for about 10 minutes in their pans before turning them onto a wire rack to cool completely.

While the cakes are baking, prepare the limoncello syrup. In a small saucepan, combine water, sugar, and limoncello over medium heat. Stir gently until the sugar is fully dissolved—this should take about 3–5 minutes. Remove from heat and cool completely.

In a large mixing bowl, combine the mascarpone cheese, powdered sugar, lemon juice, and vanilla extract. Beat on medium speed until smooth and creamy. In a separate bowl, whip the heavy cream until soft peaks form. Fold the whipped cream into the mascarpone mixture until fully incorporated.

Slice each cooled cake layer in half horizontally to create four layers. Brush each layer with limoncello syrup, then spread a layer of the mascarpone filling before adding the next sponge layer. Repeat until all layers are stacked. Chill in the refrigerator for at least 1 hour.

Drizzle remaining limoncello syrup over the top of the chilled cake. Dust with powdered sugar and garnish with lemon slices and fresh mint leaves.