- STEP 1
Preheat the oven 180C/350F/gas mark 4. Grease and fully line a 20cm springform cake tin and set aside. Coat the blackberries in the 1 tbsp flour and set aside. This helps them to stay buoyant, although you do want some sinkage for this cake as it creates a lovely pudding-like base for the cake. Set aside. In a jug, mix together the milk and lemon juice/white wine vinegar and leave to stand. This makes the buttermilk, but if you have actual buttermilk to hand feel free to use that instead, using 125ml buttermilk to replace the 125ml milk.
- STEP 2
Cream together the butter and sugar until light and fluffy. Add the beaten eggs along with the vanilla and a few tablespoons of the flour to prevent curdling. Next, alternate adding the buttermilk and flour until the ingredients are used up. Fold in the blackberries and white chocolate.
- STEP 3
Pour the mixture into the prepared tin and level the top. Sprinkle over as much demerara sugar as you like, then bake for 45 - 60 minutes, or until a skewer inserted into the centre of the cake comes out clean or with a few moist crumbs. It's meant to be a little bit squidgy on the bottom, as a great cake for serving as a pudding with some custard or cream, but it's also suitable to be eaten as it is. Leave to cool in the tin for 20-30 minutes, then turn out onto a wire rack to cool fully, or serve warm with some custard or vanilla ice cream.