To achieve a more intense hue, add food coloring to both the cake batter and the blackberry filling.
You can use either fresh or frozen blackberries—just note that frozen berries may need a bit more time to cook down.
For convenience, the cake layers and blackberry filling can be made a day ahead and stored until you're ready to assemble.
You can use either fresh or frozen blackberries—just note that frozen berries may need a bit more time to cook down.
For convenience, the cake layers and blackberry filling can be made a day ahead and stored until you're ready to assemble.