1. Set the oven at 180°c (350°f) gas 4.
2. Put the apple puree in a bowl and beat in the lemon juice and egg yolks with about 75 g/ 3 oz of the sugar.
3. Spoon into a 750 ml (1 1/4 pint) baking dish, cover, and bake for 15 minutes.
4. In a clean, grease free bowl, whisk the egg whites to stiff peaks.
5. Gradually whisk in 150 g (5 oz) of the remaining sugar, adding 15 ml (1 tbsp) at a time.
6. Pile the meringue on top of the apple mixture and sprinkle with the remaining sugar.
7. Return to the oven and bake for a further 15 minutes or until the meringue is pale golden brown.
8. Serve at once with Vanilla Custard or single cream.