Prepare Blackberry Reduction: In a medium saucepan, combine 1 cup of fresh blackberries, ½ cup of sugar, and ¼ cup of water. Cook over medium heat for about 8 to 10 minutes until thickened. Strain the mixture and let cool.

Preheat Oven: Preheat your oven to 350°F (175°C) and grease two 8-inch round cake pans.

Mix Dry Ingredients: In a medium bowl, whisk together 2 cups of flour, 1 teaspoon of baking powder, ½ teaspoon of baking soda, and ½ teaspoon of salt.

Cream Butter and Sugar: Beat together ½ cup of butter and 1 cup of sugar until light and fluffy.

Add Eggs and Flavorings: Add 2 large eggs one at a time, beating well. Mix in 1 teaspoon of vanilla extract and lemon zest.

Combine Mixtures: Gradually add the flour mixture alternating with 1 cup of buttermilk and cooled blackberry reduction.

Bake: Divide the batter between the pans and bake in the preheated oven for 28 to 32 minutes.

Cool Cakes: Let the cakes cool in the pans for 10 minutes, then invert onto a wire rack to cool completely.

Make Frosting: Beat together ½ cup of butter and 8 ounces of cream cheese until creamy. Gradually add 4 cups of powdered sugar, blackberry puree, vanilla, and salt.

Assemble Cake: Place one cake layer on a platter, spread with frosting, top with the second layer, and frost the cake.