Pre-heat your oven to 180 Deg C and line the base of a 20 cm cake
Cream the butter and caster sugar until light and fluffy.
Cut the apples into small chunks, removing the core as you go. Put
them in a bowl with the juice of the lemon, cinnamon and Demerara
sugar, toss well.
Add the eggs one at a time to the butter and sugar. Sift the flour
and baking powder together and lightly fold them into the mixture.