Now prepare the dough for the cake. Cream together demerara sugar, butter, eggs and lemon peel. Add plain flour and baking powder and mix well. Finally, add some milk to give the dough a smooth texture.
Preheat the oven to 190°C.
Spoon half of the dough into a buttered and floured round cake tin (26 cm in diameter) and layer it with the apple wedges. You can be generous with the apples because a lot of them make the cake fruitier.
Bake in the oven for about 50 minutes. Remove and leave to cool for 10 minutes. You can serve it with vanilla ice cream or simply with whipped cream.
For the dough:
300g unsalted butter
500g demerara sugar
peel of one lemon
300g plain flour
1.5 tsp. baking powder
5 tbsp. milk
For the streusel topping:
195g plain flour
144g demerara sugar
3 tsp. cinnamon
144g unsalted butter
1. Make the streusel topping by mixing flour, sugar and cinnamon. Rub in the butter until you have coarse crumbs. Wrap in cling film and chill until needed.
2. Core, peel and slice the apples into fine wedges. Drizzle with lemon juice to avoid discolouring.
3. Cream together butter, sugar, eggs and lemon peel. Add flour and baking powder and mix well. Stir in the milk.
4. Preheat the oven to 190°C. Spoon half of the dough into a buttered and floured round cake tin (26 cm in diameter) and layer with apple wedges. Add the remaining dough and sprinkle with streusel crumbs.
5. Bake for 50 minutes, and remove from the oven. Leave to cool for 10 minutes and serve warm with some vanilla ice cream.