01 -
Combine 1 1/2 cups blackberries with 2 tablespoons sugar and a splash of water in a small saucepan. Cook over medium heat for 8-10 minutes until thickened. Gently mash and strain through a fine mesh sieve to remove seeds. Allow to cool completely. Reserve 1/2 cup for the cake and 1/3 cup for the frosting.
02 -
Preheat oven to 350°F (175°C). Grease two 8-inch round cake pans and line their bottoms with parchment paper. Dust with flour to prevent sticking.
03 -
In a medium bowl, whisk together flour, baking powder, baking soda, and salt.
04 -
In a large bowl or stand mixer, beat butter and sugar at medium speed until light and fluffy, approximately 3-4 minutes.
05 -
Add eggs one at a time, beating well after each addition. Mix in vanilla extract and lemon zest if using.
06 -
In a separate bowl, whisk together buttermilk and 1/2 cup cooled blackberry puree.
07 -
Gradually add dry ingredients to the wet mixture, mixing just until combined. Incorporate the remaining blackberry puree into the batter.
08 -
Divide batter evenly between prepared pans. Bake for 30 to 45 minutes or until a toothpick inserted into the center comes out clean. Let cakes cool in pans for 10 minutes, then turn out onto wire racks to cool completely.
09 -
Beat softened butter and cream cheese until smooth and fluffy, about 2 minutes. Gradually add powdered sugar, blackberry puree, vanilla extract, and a pinch of salt. Beat until light and creamy, about 3 minutes. Chill if too soft.
10 -
Spread frosting between cake layers and over the top and sides of the cake. Garnish with fresh blackberries as desired.