Preheat the oven to 200°C / 180°C fan / 400°F / Gas mark 6
Peel, core and chop the apples into little pieces.
Place the apple pieces in a saucepan with 5 tablespoons of the water.
Cook over a medium heat, stirring often till the apples start to break down. I prefer the apples to be soft but not to have lost all of their shape - I like a bit of crunch in this dessert!
Remove from the heat and empty the softened apples into a pie dish - the one I used measures 7 inches.
Set aside whilst you make the topping.
Place the oil and the sweetener in a bowl. Whisk with either a small whisk or a fork until it is combined.
Add the remaining 2 tablespoons of boiling water and whisk again.
Add the egg and and whisk well until you have a nice smooth mixture.
Add the flour and a pinch of salt and fold in well until you have a smooth, lump free mix.
Spoon the sponge mixture over the apples and gently spread it so that it cover the apples.
Bake in the middle of the preheated oven for 18 - 22 minutes or until the top has turned a golden brown.
Serve warm with a dollop of low fat custard or fat free yogurt.