Step 1

Preheat oven to 180°C. Grease a 20cm (base measurement) round cake pan. Line the base and side with baking paper. Reserve half the blackberries. Combine 2 tsp of the caster sugar with the cinnamon in a small bowl. Reserve. Place remaining blackberries and caster sugar in a saucepan over medium heat. Bring to a simmer. Cook, stirring, for 5 mins or until the mixture thickens slightly. Set aside to cool completely.

Step 2

Use an electric mixer to beat the butter and extra caster sugar in a bowl until pale and creamy. Add eggs, 1 at a time, beating well after each addition. Add the self-raising flour and milk, in alternating batches, until just combined. Stir in the grated apple.

Step 3

Spoon one-third of the cake mixture into the prepared pan. Spoon over half the blackberry mixture. Continue layering with remaining cake mixture and blackberry mixture. Smooth the surface. Top with reserved blackberries and sliced apple. Sprinkle with the reserved cinnamon sugar.

Step 4

Place plain flour and brown sugar in a bowl. Rub in the extra butter to form large crumbs. Sprinkle over cake. Bake for 1 hour or until a skewer inserted in the centre comes out clean. Cool in the pan for 5 mins. Turn onto a wire rack. Serve warm or at room temperature.