Prepare Blackberry Puree: In a saucepan, combine 2 cups of fresh blackberries, ½ cup of sugar, and ¼ cup of water. Cook over medium heat for about 10 minutes, then strain into a bowl and let it cool.

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

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

Beat Butter and Sugar: In a mixer, beat 1 cup of butter and 1 ¾ cups of sugar until light and fluffy, then add 4 eggs one at a time.

Combine Flavors: Stir in 1 tablespoon of vanilla extract and optionally the zest of one lemon.

Blend Buttermilk and Puree: Mix 1 cup of buttermilk with 1 cup of cooled blackberry puree, then blend with the butter-sugar mixture.

Alternate Dry Ingredients: Gently add dry ingredients to the wet batter in three parts, alternating with the blackberry buttermilk mix.

Divide Batter: Evenly pour the batter into prepared cake pans and smooth the tops.

Bake: Bake for 28–32 minutes, then cool the cakes in the pans for 10 minutes before transferring to racks.

Make Frosting: Beat 8 ounces of cream cheese with ½ cup of butter, add 4 cups of powdered sugar and ½ cup blackberry puree, mixing until smooth.

Assemble Cake: Place one cake layer on a plate, spread frosting, add the second layer, and frost top and sides.