Preheat the oven to 350°F (175°C). Grease and line a 9-inch round cake pan with parchment paper.

In a mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.

Add the eggs, lemon zest, and lemon juice, mixing until well combined.

In another bowl, whisk together the flour, baking powder, and salt.

Gradually add the dry ingredients to the wet mixture, mixing until just combined.

Pour the batter into the prepared cake pan and smooth the top.

Bake for 25 minutes or until a toothpick inserted in the center comes out clean. Let cool in the pan for 10 minutes before transferring to a wire rack.

In a mixing bowl, whip the cold heavy cream until soft peaks form.

Gradually add the powdered sugar, lemon juice, lemon zest, and vanilla extract, continuing to whip until stiff peaks form.

Once the cake has cooled completely, slice it in half horizontally to create two layers.

Spread a generous layer of lemon cream filling on the bottom layer of the cake.

Place the top layer of the cake over the filling and spread the remaining lemon cream on top.

Garnish with additional lemon zest and fresh mint leaves.

Chill the cake in the refrigerator for at least 1 hour before serving.