Blackberry and blueberry streusel cake | Love Fresh Berries

Ingredients

• 50g (2 oz) plain flour
• 50g (2 oz) caster sugar
• 50g (2 oz) butter, diced
• 50g (2 oz) hazelnuts, roughly chopped
• 50 g (2 oz) hazelnuts
• 175 g (6 oz) butter, at room temperature
• 175 g (6 oz) caster sugar
• 3 eggs
• 175 g (6 oz) self-raising flour
• 1 teaspoon baking powder
• 200 g (7 oz) blackberries
• 100 g (4 oz) blueberries
• Half teaspoon ground cinnamon