1. Peel and core apples, either cut in half if small or cut into wedges. Preheat the oven to 160 degrees.
2. In a non stick frying pan, pour water onto sugar and leave to absorb for a moment. Set on a medium high heat until it turns to a clear liquid. Don’t take you eyes off it as you need to let the sugar liquid turn to caramel, but in the blink of an eye it can burn! Do not be tempted to stir or the caramel won’t form.
3. Once the sugar syrup has become golden in colour add the butter and turn down the heat by half.
4. Add apples, spooning over the liquid. Juice from the apples will make the syrup runny, but this will evaporate as the apple cooks. Leave to cook, occasionally basting the apples. Once the apples have softened and have an opaque appearance remove from the heat.
5. Spoon apples into the base of a silicone or nonstick muffin tin, a half or several wedges in each mould. Divide the caramel between each portion. Leave for several hours, preferably overnight, in the fridge to set.
6. Make cake batter by beating the margarine and sugar, and gradually add the egg. Sift and fold in flour. Spoon batter over apples, but don’t be tempted to overfill as the batter will rise.
7. Bake at 160 degrees for 15 minutes, until golden.
8. Remove from the oven, and using a rounded bladed knife, ease around the sponge so it is free. Place a large baking sheet over the muffin tray and turn out immediately, or the apple will stick.