Preheat the oven to 190c/fan 170c. Melt 50 g of the butter and 3 tablespoons of the sugar together in a saucepan and then add the sliced apples. Cook over a medium heat, stirring until they are lightly golden, about 5 minutes.

Place the flour, baking powder, cinnamon, remaining sugar and remaining butter in a bowl and rub together until the mixture resembles fine breadcrumbs. Make a well in the middle.

Mix the egg and milk together and then work into the flour mixture to form a soft dough - it will be a little wet. Turn the mixture out onto a lightly floured surface and gently knead the dough into a disc. Roll out until it is just about 2 cm thick. Using a 3 cm plain cooking cutter, stamp out about 18 rounds, rerolling the dough as necessary until used up.

Put the cooked apples into a 1.5 litre pie dish and cover with overlapping rounds of the pastry dough. Dust with the demerara and transfer to the oven. Cook for about 30 minutes until the topping is lightly golden and oozing bubbling juices. Dust with a little icing sugar and serve with vanilla ice cream.