this recipe, although I made a few minor changes along the way. For a start, I didn't have enough butter in the house, so I decided to use coconut oil instead. As I reduced the amount of fat used in the recipe, to compensate for coconut oil being 100% fat, I thought I would need more liquid in the cake batter, but I only needed about half the volume of milk suggested in the recipe (and a couple of tablespoons of rum), to give a good dropping consistency. If I'd used the amount of liquid originally suggested, I'm not sure the blackberries would have stayed on the surface.
These are the ingredients I used to make the sponge base, which was spread into a 22cm springform tin: 160g coconut oil, 170g caster sugar, 2 large eggs, 1 teaspoon vanilla paste, 2 tablespoons rum, 150g SR flour, 150g plain flour, enough milk to give a dropping consistency (about 100mls). On top of this I spread 230g blackberries in a single layer, then topped with a crumble mix made from 75g plain flour, 50g butter, 55g light muscovado sugar and 45g desiccated coconut. This was baked at 180C for 85 minutes, covered with foil after an hour.
I wasn't expecting a light sponge, as there was double the amount of flour to fat and sugar, and half of it was plain flour, but this really was a dense cake! It was very tasty though, as it wasn't over-sweet and the tang of the blackberries was still evident. The coconut in the crumble added a good flavour and texture, and it was nice to use blackberries with something other than apples.
Because of the denseness of the sponge, this would probably have been better as a warm dessert, with custard, as suggested. I think if I made it again as a cake, I would use all SR flour to try to make it a little lighter.