Preheat your oven to 190 degrees and lightly grease a 20cm round oven proof dish.
Add 200 grams of water to your Thermomix bowl and add the apple quarters, cinnamon and caster sugar. Cook for 10 minutes, varoma temperature, speed 1 on REVERSE.
Retain 2 tablespoons (40 grams) of the cooking liquid before draining the rest and set aside until needed. I find it easiest to pour the apples in the basket and let the fluid drain.
Place the softened butter, caster sugar and the retained liquid from the apples into the Thermomix bowl and mix for 10 seconds, speed 4.
Add the egg, self raising flour and a pinch of salt and mix for 10 seconds, speed 3 to combine.
Scrape down the sides of your Thermomix bowl and mix for a further 5 seconds, speed 4 to combine.
Place the stewed apples over the base of the baking dish and spoon the cake mixture over the top.
Place the pudding into the preheated oven and bake for 35 minutes or until the cake has cooked through when tested with a skewer.
Carefully remove the pudding from the oven and allow it to cool slightly before serving.