Preheat oven to 350 degrees. Grease and flour two 9-inch cake pans. Set aside.

In a large bowl, sift the flour, baking powder, baking soda, and salt together. Set aside.

In the bowl of an electric stand mixer, using the paddle attachment, beat butter on medium speed with the sugar until it forms a soft paste, approximately 1 minute. Add the eggs one at a time, beating after each until incorporated, making sure to scrape down the sides of the bowl as needed.

On low speed, alternate between adding the flour mixture and the buttermilk, working in two batches for each. Once fully incorporated, beat in the vanilla bean paste.

Divide the batter evenly between the two cake pans. Bake in the oven for 25 to 30 minutes or until a cake tester comes out clean. Transfer the pans to wire racks and cool for at least 15 to 20 minutes, before turning out the cakes to cool completely.

Once the cakes are cool, use a serrated knife to cut off the domes of each cake so the cake tops are flat. Set aside.

In a clean bowl, using a stand mixer or electric mixer, beat the heavy cream with the sugar until it forms soft peaks. Add the mint leaves and lemon zest, and continue to beat until the cream forms stiff peaks.

Add one of the cakes to your desired serving platter or cake stand. Spread a thick even layer of the whipped cream on top of the cake. Add the other cake on top and decorate as desired with remaining whipped cream frosting and berries. Garnish the top with fresh mint leaves and serve!