Inis Meáin apple sponge tart

For the pastry:

225g butter

50g caster sugar

2 eggs

350g white flour

For the sponge:

250g butter

350g caster sugar

6 eggs

350g flour

2 rounded tsp baking powder

2 tbsp milk

For the filling:

6 large cooking apples, peeled, cored and sliced

1 heaped tbsp brown sugar

1 rectangular baking tray 40 x 30 x 4cm (16 x 12 x 1.5in)