For the cake: Sieve flour, baking powder, salt and sugar into a bowl. Rub butter in until the mixture resembles fine breadcrumbs. Stir in egg and milk. Spread mixture into a well greased pie dish.
For the Topping: Arrange sliced apples in a circular pattern to cover cake completely. Mix together sugar, cinnamon and nutmeg, sprinkle over apples. Drizzle with melted butter.
Bake in preheated oven for about 30 minutes.
Meanwhile, make the glaze by mixing together apricot jam and water until smooth. Pass through a sieve and set aside.