• Preheat your oven to 350°F (175°C). Grease and flour three 8-inch round cake pans.
• In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
• In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.
• Beat in the eggs, one at a time, followed by the vanilla extract, lemon zest, and lemon juice.
• Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk, beginning and ending with the dry ingredients. Mix until just combined.
• Gently fold in the fresh blueberries, being careful not to overmix.
• Divide the batter evenly among the prepared cake pans and smooth the tops with a spatula.
• Bake in the preheated oven for 20-25 minutes, or until a toothpick inserted into the center of the cakes comes out clean.
• Allow the cakes to cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.

For the frosting:

• In a large mixing bowl, beat the softened butter until creamy.
• Gradually add the powdered sugar, one cup at a time, beating well after each addition.
• Add the lemon juice, lemon zest, and vanilla extract, and beat until smooth.
• If the frosting is too thick, gradually add heavy cream, one tablespoon at a time, until the desired consistency is reached.

Assembly:

• Once the cakes are completely cooled, place one layer on a serving plate or cake stand.
• Spread a layer of frosting over the top of the cake layer.
• Place another cake layer on top and repeat the process until all layers are stacked.
• Use the remaining frosting to cover the top and sides of the cake, creating a rustic naked appearance.
• Decorate the top of the cake with fresh blueberries, lemon slices, and mint leaves for a beautiful finishing touch.