Heat oven to 200C, Gas 6, 400F. Grease your baking tray.
Make the custard, by adding custard powder, 1 1/2 tbsp sugar and the milk to a pan and heat until thick. (see photo). Leave to cool until tepid.
Peel, core and slice the apples to 1/2 cm thick. Squeeze lemon juice over them to prevent from browning.
Get your flaky pastry out of the fridge, divide into two and roll e5. Lengthways, arrange the apple slices so they cover just less than half the pastry (see photo), and spread the custard over the apples. Keep 1 1/2 cm space free around the edges. (see photo)
Brush the edges with milk and fold the pastry over the filling, sealing the edges.
Brush the TOP with milk, and NOT the edges. If you brush the edges, it will prevent the pastry from rising! Sprinkle with the remainder of the sugar.8. Put it in the hot oven and bake for 25 – 35 minutes or until golden brown. The time will vary depending on how big or small you choose to make your parcels. Make sure the oven has reached the correct temperature before cooking as this will greatly help the flakiness and rising of the pastry.
Allow cooling slightly. This is best eaten ‘warm’ as opposed to ‘hot’, either on its own or with a scoop of ice cream.