I made this cake today for a potluck & it was a hit. The recipe is from Living Locurto. Here is the link to her printable recipe page: Blackberry cake. Next time I will use more berries – this was about what the recipe said, but these were very big berries and it could have had more. I also used Softasilk cake flour, not self-rising flour, because I had it and not the other. My understanding is that you can substitute 1 cup minus 1 tablespoon all-purpose flour plus 1 1/2 teaspoons baking powder and 1/8 teaspoon salt for one cup of self-rising flour but there was nothing wrong with it as it turned out.
The Buttercream Frosting recipe I used:
1 1/4 cup butter, room temperature
2 teaspoons clear vanilla (mine wasn’t)
1 teaspoon almond extract
8-9 teaspoons milk
7 1/2 cups (2 pounds) powdered sugar
Beat butter, vanilla and almond in a medium bowl at medium speed until creamy. Gradually add milk and powdered sugar, scraping bowl as needed. Beat on high speed adding additional milk by the tablespoon until desired spreading consistency is achieved.