Preheat your oven to the appropriate temperature for baking.
In a mixing bowl, combine the self-raising flour, Stork or butter, sugar, and eggs. Mix until well blended.
Fold in the chopped apples gently into the batter.
In a saucepan, melt the 60 g of salted butter and add the light brown sugar and 2 tsp of cinnamon. Stir until combined.
Add the water mixed with cornflour to the saucepan and cook until the mixture thickens slightly.
Pour the apple mixture into a prepared baking dish and then drizzle the butter and sugar mixture over the top.
For the crumble topping, mix the cold diced salted butter with plain flour, sugar, and 2 tsp of cinnamon until it resembles coarse crumbs.
Sprinkle the crumble topping evenly over the apple mixture.
Bake in the preheated oven until the cake is golden brown and a skewer inserted into the center comes out clean.
Allow to cool slightly before serving.
