Melt the baking chocolate so it's ready for later. Sift the dry ingredients into a large bowl. Add sour cream, softened butter, blackberry sauce & beat with an electric mixer on high for 2 min. Add melted chocolate, eggs & vanilla.
Beat on high again for 2 minutes until smooth. Spread into a 13 x 9 inch baking pan lined with parchment and bake at 350F for 25 to 30 min.
Allow the cake to cool and top with the ganache. The ganache is what brings this whole dessert together. The key is using super dark chocolate to offset the cream cheese frosting.