Pre-heat oven to 180 degrees celsius (fan-forced) and line the base and sides of an 18 x 28cm slice tin with baking paper.
Add the butter to the Thermomix bowl and cook for 3 minutes, 60 degrees, Speed 2 or until melted.
Add the self-raising flour, caster sugar, coconut and vanilla extract and mix for 10 seconds, Speed 4. Scrape down the sides of the bowl and mix for a further 5 seconds, Speed 4.
Transfer the mixture to the prepared slice tray and push down with the back of a spoon to flatten the surface. Bake for 15 minutes before allowing to cool for 10 minutes.
Add the tinned apples and gently smooth the surface.
Add the sour cream and use a spatula to gently smooth.
Sprinkle with cinnamon sugar (or ground cinnamon) and return to the. oven to bake for a further 20 minutes.
Carefully remove from the oven and allow the slice to completely cool before cutting into pieces.
Store in an airtight container in the fridge for up to five days.