Preheat your oven to 350°F (175°C). Grease and line two 8-inch cake pans with parchment paper.

In a separate bowl, sift together the all-purpose flour, baking powder, and salt. In a large mixing bowl, beat the eggs and granulated sugar together until pale and thick.

Gently fold in the vanilla extract and lemon zest. Gradually incorporate the dry ingredients until just combined.

Divide the batter equally between your prepared cake pans and bake for 18-20 minutes.

In a saucepan, combine water, granulated sugar, and limoncello liqueur. Heat until the sugar has dissolved, remove from heat and let cool.

In a bowl, beat mascarpone cheese, powdered sugar, lemon juice, and vanilla until creamy. In a separate bowl, whip heavy cream until soft peaks form and fold into the mascarpone mixture.

Slice the cooled sponge cakes horizontally, brush each layer with limoncello syrup, and spread mascarpone filling between layers. Chill the assembled cake for at least one hour.

Drizzle limoncello glaze over the top, dust with powdered sugar, and garnish with fresh lemon slices and mint. Serve.