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

In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy, about 3-4 minutes.

Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract and lemon zest.

In a separate bowl, whisk together the flour, baking powder, baking soda, and salt.

Gradually add the dry ingredients to the butter mixture, alternating with the buttermilk. Start and end with the flour mixture, mixing until just combined.

Divide the batter evenly between the prepared cake pans. Bake for 25-30 minutes, or until a toothpick inserted in the center comes out clean. Let the cakes cool in the pans for 10 minutes before transferring to wire racks to cool completely.

While the cakes are cooling, prepare the lemon cream. In a medium bowl, whip the heavy cream until soft peaks form. Gradually add the powdered sugar and lemon juice, continuing to whip until stiff peaks form.

Once the cakes are completely cool, place one layer on a serving plate. Spread a generous layer of lemon cream on top. Place the second layer on top and frost the top and sides with the remaining lemon cream.

Garnish with fresh lemon slices and mint leaves if desired. Chill the cake in the refrigerator for at least 1 hour before serving to allow the flavors to meld.