Blackberry and plum streusel cake
- Preheat the oven to 170 degC.
- Lightly grease a 22cm-square cake tin and line with baking paper, letting the paper overhang slightly around the rim to assist with removing the streusel once cooked.
- To make the topping, place 50g of the flour in a bowl, add the cold cubed butter and rub in until the mixture resembles coarse breadcrumbs. Mix in the brown sugar and set aside.
- To make the cake, sift the remaining flour, the baking powder and a pinch of sea salt into a bowl. In a large bowl, cream the softened butter and caster sugar with electric beaters.
- Add the eggs, one at a time, beating well after each addition.
- Tip in the dry ingredients, alternating with the sour cream, while being careful not to over-mix (some small lumps of flour are okay).
- Pour the batter into the lined cake tin and scatter over the plums and 150g of the blackberries, then finish with the topping.
- Bake for 55-60 minutes, or until a skewer inserted into the centre comes out clean.
- Allow the streusel to cool a little before lifting it out of the tin.
- Serve warm or at room temperature with the remaining blackberries and cream.