Preheat your oven to 350°F (175°C). Grease two 9-inch round cake pans with butter or non-stick spray and line the bottoms with parchment paper.

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

In a separate bowl, whisk together buttermilk, blackberry purée, lemon juice, and vanilla extract until fully combined.

In a mixing bowl, combine sugar and vegetable oil, beating them together until creamy. Add eggs one at a time, mixing well. Gradually alternate between adding dry mixture and wet ingredients to the sugar mixture, stirring gently until just combined.

Divide the batter evenly between the two prepared pans and smooth the tops. Bake for 30–35 minutes until a toothpick comes out clean. Cool for 10 minutes, then carefully remove from pans to cool completely.

In a mixing bowl, beat cream cheese and butter until fluffy. Gradually add powdered sugar, mixing until combined. Stir in blackberry purée and vanilla extract, then chill.

Once the cakes are cool, level them if necessary. Place one layer on a serving plate, spread frosting on top, place the second layer, and frost the sides and top. Decorate with blackberries, edible flowers, and drizzle with blackberry glaze.