Preheat the oven to 350°F (175°C). Grease and flour two 9-inch round cake pans.

Cream together softened butter and sugar until light and fluffy, about 3-5 minutes.

Beat in the eggs one at a time, then add lemon zest, lemon juice, and vanilla extract, mixing until combined.

In a separate bowl, whisk together flour, baking powder, baking soda, and salt. Gradually fold this into the wet mixture, alternating with buttermilk.

Divide the batter between prepared pans and bake for 28-30 minutes, or until a toothpick comes out clean.

Allow cakes to cool in pans for 10 minutes before transferring to wire racks.

In a chilled bowl, whip the heavy whipping cream until stiff peaks form.

Gradually add powdered sugar and vanilla extract, folding to combine. Optionally, fold in lemon curd.

Place one cake layer on a serving platter, spread Chantilly cream on top, then add the second layer.

Frost the top and sides with remaining Chantilly cream.

Garnish with lemon slices, lemon zest, and mint leaves. Refrigerate the cake for at least an hour before serving.